Encyclopaedia Britannica Volume 3, Part 1, Slice 1 Part 16

AVONIAN, in geology, the name proposed by Dr A. Vaughan in 1905 (_Q.J.G.S._ vol. lxi. p. 264) for the rocks of Lower Carboniferous age in the Avon gorge at Bristol. The Avonian stage appears to embrace precisely the same rocks and fossil-zones as the earlier designation "Dinantien" (see CARBONIFEROUS SYSTEM); but its substages, being founded upon different local conditions and a different interpretation of the zonal fossils, do not correspond exactly with those of the French and Belgian geologists.

Substages. ZONES. Substages.

{ Kidwellian { _Dibunophyllum_ } } { { _Seminula_ } Viseen } Avonian { } } Dinantien { { _Syringothyris_ } } { Clevedonian { } { { _Zaphrentis_ } Tournaisien } { { _Cleistopora_ } }

The upper Avonian (Kidwellian) is well developed about Kidwelly in Carmarthenshire. The lower substage (Clevedonian) is well displayed near Clevedon in Somerset.

See A. Vaughan, "The Carboniferous Limestone Series (Avonian) of the Avon Gorge," _Proc. Bristol Naturalists' Soc._, 4th series, vol. i. pt. 2, 1906, pp. 74-168 (many plates); and T. F. Sibley, "On the Carboniferous Limestone (Avonian) of the Mendip area (Somerset)," _Q.J.G.S._ vol. lxii., 1906, pp.

324-380 (plates).

(J. A. H.)

AVONMORE, BARRY YELVERTON, 1ST VISCOUNT (1736-1805), Irish judge, was born in 1736. He was the eldest son of Frank Yelverton of Blackwater, Co. Cork.

Educated at Trinity College, Dublin, he was for some years an a.s.sistant master under Andrew Buck in the Hibernian Academy. In 1761 he married Miss Mary Nugent, a lady of some fortune, and was then enabled to read for the bar. He was called in 1764, his success was rapid, and he took silk eight years afterwards. He sat in the Irish parliament as member successively for the boroughs of Donegal and Carrickfergus, becoming attorney-general in 1782, but was elevated to the bench as chief baron of the exchequer in 1783. He was created (Irish) Baron Avonmore in 1795, and in 1800 (Irish) viscount. Among his colleagues at the Irish bar Yelverton was a popular and charming companion. Of insignificant appearance, he owed his early successes to his remarkable eloquence, which made a great impression on his contemporaries; as a judge, he was inclined to take the view of the advocate rather than that of the impartial lawyer. He gave his support to Grattan and the Whigs during the greater part of his parliamentary career, but in his latter days became identified with the court party and voted for the union, for which his viscounty was a reward. He had three sons and one daughter, and the t.i.tle has descended in the family.

AVRANCHES, a town of north-western France, capital of an arrondiss.e.m.e.nt in the department of Manche, 87 m. S. of Cherbourg on the Western railway.

Pop. (1906) 7186. It stands on a wooded hill, its botanical gardens commanding a fine view westward of the bay and rock of St Michel. At the foot of the hill flows the river See, which at high tide is navigable from the sea. The town is surrounded by avenues, which occupy the site of the ancient ramparts, remains of which are to be seen on the north side.

Avranches was from 511 to 1790 a bishop's see, held at the end of the 17th century by the scholar Daniel Huet; and its cathedral, destroyed as insecure in the time of the first French Revolution, was the finest in Normandy. Its site is now occupied by an open square, one stone remaining to mark the spot where Henry II. of England received absolution for the murder of Thomas Becket. The churches of Notre-Dame des Champs and St Saturnin are modern buildings in the Gothic style. The ancient episcopal palace is now used as a court of justice; a public library is kept in the hotel de ville. In the public gardens there is a statue of General Jean Marie Valhubert, killed at Austerlitz. Avranches is seat of a sub-prefect and has a tribunal of first instance and a communal college.

Leather-dressing is the chief industry; steam-sawing, brewing and dyeing are also carried on, and horticulture flourishes in the environs. Trade is in cider, cattle, b.u.t.ter, flowers and fruit, and there are salmon and other fisheries.

Avranches, an important military station of the Romans, was in the middle ages chief place of a county of the duchy of Normandy. It sustained several sieges, the most noteworthy of which, in 1591, was the result of its opposition to Henry IV. In 1639 Avranches was the focus of the peasant revolt against the salt-tax, known as the revolt of the Nu-pieds.

AWADIA and FADNIA, two small nomad tribes of pure Arab blood living in the Bayuda desert, Anglo-Egyptian Sudan, between the wells of Jakdul and Metemma. They are often incorrectly cla.s.sed as Ja'alin. They own numbers of horses and cattle, the former of the black Dongola breed. At the battle of Abu Klea (17th of January 1885) they were conspicuous for their courage in riding against the British square.

See _Anglo-Egyptian Sudan_, edited by Count Gleichen (London, 1905).

AWAJI, an island belonging to j.a.pan, situated at the eastern entrance of the Inland Sea, having a length of 32 m., an extreme breadth of 16 m., and an area of 218 sq. m., with a population of about 190,000. It is separated on the south from the island of Shikoku by the Naruto channel, through which, in certain conditions of the tide, a remarkable torrential current is set up. The island is celebrated for its exquisite scenery, and also for the fact that it is traditionally reputed to have been the first of the j.a.panese islands created by the deities Izanagi and Izanami. The loftiest peak is Yuruuba-yama (1998 ft.), the most picturesque Sen-zan (1519 ft.).

Awaji is noted for a peculiar manufacture of pottery.

AWARD (from O. Fr. _ewart_, or _esguart_, cf. "reward"), the decision of an arbitrator. (See ARBITRATION.)

AWE, LOCH, the longest freshwater lake in Scotland, situated in mid-Argyllshire, 116 ft. above the sea, with an area of nearly 16 sq. m. It has a N.E. to S.W. direction and is fully 23 m. long from Kilchurn Castle to Ford, its breadth varying from 1/3 of a mile to 3 m. at its upper end, where it takes the shape of a crescent, one arm of which runs towards Glen Orchy, the other to the point where the river Awe leaves the lake. The two ends of the loch are wholly dissimilar in character, the scenery of the upper extremity being majestic, while that of the lower half is pastoral and tame. Of its numerous islands the best-known is Inishail, containing ruins of a church and convent, which was suppressed at the Reformation. At the extreme north-eastern end of the lake, on an islet which, when the water is low, becomes part of the mainland, stand the imposing ruins of Kilchurn Castle. Its romantic surroundings have made this castle a favourite subject of the landscape painter. Dalmally, about 2 m. from the loch, is one of the pleasantest villages in the Highlands and has a great vogue in midsummer. The river Awe, issuing from the north-western horn of the loch, affords excellent trout and salmon fishing.

AWL (O. Eng. _ael_; at one time spelt _nawl_ by a confusion with the indefinite article before it), a small hand-tool for piercing holes.

AXE (O. Eng. _aex_; a word common, in different forms, in the Teutonic languages, and akin to the Greek [Greek: axine]; the _New English Dictionary_ prefers the spelling "ax"), a tool or weapon, taking various shapes, but, when not compounded with some distinguishing word (_e.g._ in "pick-axe"), generally formed [v.03 p.0068] by an edged head fixed upon a handle for striking. A "hatchet" is a small sort of axe.

AXHOLME, an island in the north-west part of Lincolnshire, England, lying between the rivers Trent, Idle and Don, and isolated by drainage channels connected with these rivers. It consists mainly of a plateau of slight elevation, rarely exceeding 100 ft., and comprises the parishes of Althorpe, Belton, Epworth, Haxey, Luddington, Owston and Crowle; the total area being about 47,000 acres. At a very early period it would appear to have been covered with forest; but this having been in great measure destroyed, it became in great part a swamp. In 1627 King Charles I., who was lord of the island, entered into a contract with Cornelius Vermuyden, a Dutchman, for reclaiming the meres and marshes, and rendering them fit for tillage. This undertaking led to the introduction of a large number of Flemish workmen, who settled in the district, and, in spite of the violent measures adopted by the English peasantry to expel them, retained their ground in sufficient numbers to affect the physical appearance and the accent of the inhabitants to this day. The princ.i.p.al towns in the isle are Crowle (pop. 2769) and Epworth. The Axholme joint light railway runs north and south through the isle, connecting Goole with Haxey junction; and the Great Northern, Great Eastern and Great Central lines also afford communications. The land is extremely fertile. The name, properly Axeyholm (cf. Haxey), is hybrid, _Ax_ being the Celtic _uisg_, water; _ey_ the Anglo-Saxon for island; and _holm_ the Norse word with the same signification.

AXILE, or AXIAL, a term (= related to the axis) used technically in science; in botany an embryo is called axile when it has the same direction as the axis of the seed.

[Ill.u.s.tration]

AXINITE, a mineral consisting of a complex aluminium and calcium boro-silicate with a small amount of basic hydrogen; the calcium is partly replaced in varying amounts by ferrous iron and manganese, and the aluminium by ferric iron: the formula is HCa_3BAl_2(SiO_4)_4. The mineral was named (from [Greek: axine], an axe) by R. J. Hauy in 1799, on account of the characteristic thin wedge-like form of its anorthic crystals. The colour is usually clove-brown, but rarely it has a violet tinge (on this account the mineral was named yanolite, meaning violet stone, by J. C.

Delametherie in 1792). The best specimens are afforded by the beautifully developed transparent gla.s.sy crystals, found with albite, prehnite and quartz, in a zone of amphibolite and chlorite-schists at Le Bourg d'Oisans in Dauphine. It is found in the greenstone and hornblende-schists of Batallack Head near St Just in Cornwall, and in diabase in the Harz; and small ones in Maine and in Northampton county, Pennsylvania, U.S.A. Large crystals have also been found in j.a.pan. In its occurrence in basic rather than in acid eruptive rocks, axinite differs from the boro-silicate tourmaline, which is usually found in granite. The specific gravity is 3.28. The hardness of 6-7, combined with the colour and transparency, renders axinite applicable for use as a gemstone, the Dauphine crystals being occasionally cut for this purpose.

(L. J. S.)

AXIOM (Gr. [Greek: axioma]), a general proposition or principle accepted as self-evident, either absolutely or within a particular sphere of thought.

Each special science has its own axioms (cf. the Aristotelian [Greek: archai], "first principles") which, however, are sometimes susceptible of proof in another wider science. The Greek word was probably confined by Plato to mathematical axioms, but Aristotle (_a.n.a.l. Post._ i. 2) gave it also the wider significance of the ultimate principles of thought which are behind all special sciences (_e.g._ the principle of contradiction). These are apprehended solely by the mind, which may, however, be led to them by an inductive process. After Aristotle, the term was used by the Stoics and the school of Ramus for a proposition simply, and Bacon (_Nov. Organ._ i.

7) used it of any general proposition. The word was reintroduced in modern philosophy probably by Rene Descartes (or by his followers) who, in the search for a definite self-evident principle as the basis of a new philosophy, naturally turned to the familiar science of mathematics. The axiom of Cartesianism is, therefore, the _Cogito ergo sum_. Kant still further narrowed the meaning to include only self-evident (intuitive) synthetic propositions, _i.e._ of s.p.a.ce and time. The nature of axiomatic certainty is part of the fundamental problem of logic and metaphysics.

Those who deny the possibility of all non-empirical knowledge naturally hold that every axiom is ultimately based on observation. For the Euclidian axioms see GEOMETRY.

AXIS (Lat. for "axle"), a word having the same meaning as axle, and also used with many extensions of this primary meaning. It denotes the imaginary line about which a body or system of bodies rotates, or a line about which a body or action is symmetrically disposed. In geometry, and in geometrical crystallography, the term denotes a line which serves to aid the orientation of a figure. In anatomy, it is, among other uses, applied to the second cervical vertebra, and in botany it means the stem.

AXLE (in Mid. Eng. _axel-tre_, from O. Norweg. _oxull-tre_, cognate with the O. Eng. _aexe_ or _eaxe_, and connected with Sansk. _aksha_, Gr. [Greek: axon], and Lat. _axis_), the pin or spindle on which a wheel turns. In carriages the axle-tree is the bar on which the wheels are mounted, the axles being strictly its thinner rounded prolongations on which they actually turn. The pins which pa.s.s through the ends of the axles and keep the wheels from slipping off are known as axle-pins or "linch-pins,"

"linch" being a corruption, due to confusion with "link," of the Old English word for "axle," _lynis_, cf. Ger. _Lunse_.

AX-LES-THERMES, a watering place of south-western France, in the department of Ariege, at the confluence of the Ariege with three tributaries, 26 m.

S.S.E. of Foix by rail. Pop. (1906) 1179. Ax (Aquae), situated at a height of 2300 ft., is well known for its warm sulphur springs (77-172 F.), of which there are about sixty. The waters, which were used by the Romans, are efficacious in the treatment of rheumatism, skin diseases and other maladies.

AXMINSTER, a market-town in the Honiton parliamentary division of Devonshire, England, on the river Axe, 27 m. E. by N. of Exeter by the London & South-Western railway. Pop. (1901) 2906. The minster, dedicated to St Mary the Virgin, ill.u.s.trates every style of architecture from Norman to Perpendicular. There are in the chancel two freestone effigies, perhaps of the 14th century, besides three sedilia, and a piscina under arches.

Axminster was long celebrated for the admirable quality of its carpets, which were woven by hand, like tapestry. Their manufacture was established in 1755. Their name is preserved, but since the seat of this industry was removed to Wilton near Salisbury, the inhabitants of Axminster have found employment in brush factories, corn mills, timber yards and an iron foundry. Cloth, drugget, cotton, leather, gloves and tapes are also made.

Coaxdon House, the birthplace in 1602 of Sir Symonds d'Ewes, the Puritan historian, is about 2 m. distant, and was formerly known as St Calyst.

Axminster (Axemystre) derives its name from the river Axe and from the old abbey church or minster said to have been built by King aethelstan. The situation of Axminster at the intersection of the two great ancient roads, Iknield Street and the Fosse Way, and also the numerous earthworks and hill-fortresses in the neighbourhood indicate a very early settlement.

There is a tradition that the battle of Brunanburh was fought in the valley of the Axe, and that the bodies of the Danish princes who perished in action were buried in Axminster church. According to Domesday, Axminster was held by the king. In 1246 Reginald de Mohun, then lord of the manor, founded a Cistercian abbey at Newenham within the parish of Axminster, granting it a Sat.u.r.day market and a fair on Midsummer day, and the next year made over to the monks from Beaulieu the manor and hundred of Axminster. The abbey was dissolved in 1539. The midsummer fair established by Reginald de Mohun is still held.

See _Victoria County History--Devon_; James Davidson, _British and Roman Remains in the Vicinity of Axminster_ (London, 1833).

AXOLOTL, the Mexican name given to larvae salamanders of the genus _Amblystoma_. It required the extraordinary ac.u.men of the great Cuvier at once to recognize, when the first specimens [v.03 p.0069] of the _Gyrinus edulis_ or _Axolotl_ of Mexico were brought to him by Humboldt in the beginning of the 19th century, that these Batrachians were not really related to the Perennibranchiates, such as _Siren_ and _Proteus_, with which he was well acquainted, but represented the larval form of some air-breathing salamander. Little heed was paid to his opinion by most systematists, and when, more than half a century later, the axolotl was found to breed in its branchiferous condition, the question seemed to be settled once for all against him, and the genus _Siredon_, as it was called by J. Wagler, was unanimously maintained and placed among the permanent gill-breathers.

It seemed impossible to admit that an animal which lives for years without losing its gills, and is able to propagate in that state, could be anything but a perfect form. And yet subsequent discoveries, which followed in rapid succession, have established that _Siredon_ is but the larval form of the salamander _Amblystoma_, a genus long known from various parts of North America; and Cuvier's conclusions now read much better than they did half a century after they were published. Before reviewing the history of these discoveries, it is desirable to say a few words of the characters of the axolotl (larval form) and of the _Amblystoma_ (perfect or imago form).

The axolotl has been known to the Mexicans from the remotest times, as an article of food regularly brought from neighbouring lakes to the Mexico market, its flesh being agreeable and wholesome. Francisco Hernandez (1514-1578) has alluded to it as _Gyrinus edulis_ or _atolocatl_, and as _lusus aquarum_, _piscis ludicrus_, or _axolotl_, which latter name has remained in use, in Mexico and elsewhere, to the present day. But for its large size--it grows to a length of eleven inches--it is a nearly exact image of the British newt larvae. It has the same moderately long, plump body, with a low dorsal crest, the continuation of the membrane bordering the strongly compressed tail; a large thick head with small eyes without lids and with a large pendent upper lip; two pairs of well-developed limbs, with free digits; and above all, as the most characteristic feature, three large appendages on each side of the back of the head, fringed with filaments which, in their fullest development, remind one of black ostrich feathers. These are the external gills, through which the animal breathes the oxygen dissolved in the water. The jaws are provided with small teeth in several rows, and there is an elongate patch of further teeth on each side of the front of the palate (inserted on the vomerine and palatine bones). The colour is blackish, or of a dark olive-grey or brownish grey with round black spots or dots.

The genus _Amblystoma_ was established by J. J. Tschudi in 1838 for various salamanders from North America, which had previously been described as _Lacerta_ or _Salamandra_, and which, so far as general appearance is concerned, differ little from the European salamanders. The body is smooth and shiny, with vertical grooves on the sides, the tail is but feebly compressed, the eye is moderately large and provided with movable lids, and the upper lip is nearly straight. But the dent.i.tion of the palate is very different; the small teeth, which are in a single row, as in the jaws, form a long transverse, continuous or interrupted series behind the inner nares or choanae. The animal leaves the water after completing its metamorphosis, the last stage of which is marked by the loss of the gills. One of the largest and most widely distributed species of this genus, which includes about twenty, is the _Amblystoma tigrinum_, an inhabitant of both the east and west of the United States and of a considerable part of the cooler parts of Mexico. It varies much in colour, but it may be described as usually brown or blackish, with more or less numerous yellow spots, sometimes arranged in transverse bands. It rarely exceeds a length of nine inches. This is the _Amblystoma_ into which the axolotl has been ascertained to transform. It is generally admitted that the axolotls which were kept alive in Europe and were particularly abundant between 1870 and 1880 are all the descendants of a stock bred in Paris and distributed chiefly by dealers, originally, we believe, by the late P. Carbonnier.

Close in-breeding without the infusion of new blood is probably the cause of the decrease in their numbers at the present day, specimens being more difficult to procure and fetching much higher prices than they did formerly, at least in England and in France.

The original axolotls, from the vicinity of Mexico City, it is believed, arrived at the Jardin d'Acclimatation, Paris, late in 1863. They were thirty-four in number, among which was an albino, and had been sent to that inst.i.tution, together with a few other animals, by order of Marshal Forey, who was appointed commander-in-chief of the French expeditionary force to Mexico after the defeat of General Lorencez at Puebla (May 5th, 1862), and returned to France at the end of 1863, after having handed over the command to Marshal (then General) Bazaine. Six specimens (five males and one female) were given by the Societe d'Acclimatation to Professor A. Dumeril, the administrator of the reptile collection of the Jardin des Plantes, the living specimens of which were at that time housed in a very miserable structure, situated at a short distance from the comparatively sumptuous building which was erected some years later and opened to the public in 1874. Soon after their arrival at the Jardin d'Acclimatation, some of the axolotls sp.a.w.ned, but the eggs, not having been removed from the aquarium, were devoured by its occupants. At the same time, in the Jardin des Plantes, the single female axolotl also sp.a.w.ned, twice in succession, and a large number of young were successfully reared. This, it then seemed, solved the often-discussed question of the perennibranchiate nature of these Batrachians. But a year later, the second generation having reached s.e.xual maturity, new broods were produced, and out of these some individuals lost their gills and dorsal crest, developed movable eyelids, changed their dent.i.tion, and a.s.sumed yellow spots,--in fact, took on all the characters of _Amblystoma tigrinum_. However, these transformed salamanders, of which twenty-nine were obtained from 1865 to 1870, did not breed, although their branchiate brethren continued to do so very freely.

It was not until 1876 that the axolotl in its _Amblystoma_ state, offspring of several generations of perennibranchiates, was first observed to sp.a.w.n, and this again took place in the reptile house of the Jardin des Plantes, as reported by Professor E. Blanchard.

The original six specimens received in 1864 at the Jardin des Plantes, which had been carefully kept apart from their progeny, remained in the branchiate condition, and bred eleven times from 1865 to 1868, and, after a period of two years' rest, again in 1870. According to the report of Aug.

Dumeril, they and their offspring gave birth to 9000 or 10,000 larvae during that period. So numerous were the axolotls that the Paris Museum was able to distribute to other inst.i.tutions, as well as to dealers and private individuals, over a thousand examples, which found their way to all parts of Europe, and numberless specimens have been kept in England from 1866 to the present day. The first specimens exhibited in the London Zoological Gardens, in August 1864, were probably part of the original stock received from Mexico by the Societe d'Acclimatation but do not appear to have bred.

"White" axolotls, albinos of a pale flesh colour, with beautiful red gills, have also been kept in great numbers in England and on the continent. They are said to be all descendants of one albino male specimen received in the Paris Museum menagerie in 1866, which, paired with normal specimens in 1867 and 1868, produced numerous white offspring, which by selection have been fixed as a permanent race, without, according to L. Vaillant, showing any tendency to reversion. We are not aware of any but two of these albinos having ever turned into the perfect _Amblystoma_ form, as happened in Paris in 1870, the albinism being retained.

Thus we see that in our aquariums most of the axolotls remain in the branchiate condition, transformed individuals being on the whole very exceptional. Now it has been stated that in the lakes near Mexico City, where it was first discovered, the axolotl _never_ transforms into an _Amblystoma_. This the present writer is inclined to doubt, considering that he has received examples of the normal _Amblystoma tigrinum_ from various parts of Mexico, and that Alfred Duges has described an _Amblystoma_ from mountains near Mexico City; at the same time he feels very [v.03 p.0070] suspicious of the various statements to that effect which have appeared in so many works, and rather disposed to make light of the ingenious theories launched by biological speculators who have never set foot in Mexico, especially Weismann's picture of the dismal condition of the salt-incrusted surroundings which were supposed to have hemmed in the axolotl--the brackish Lago de Texcoco, the largest of the lakes near Mexico, being evidently in the philosopher's mind.

Thanks to the enthusiasm of H. Gadow during his visit to Mexico in the summer of 1902, we are now better informed on the conditions under which the axolotl lives near Mexico City. First, he ascertained that there are no axolotls at all in the Lago de Texcoco, thus disposing at once of the Weismannian explanation; secondly, he confirmed A. Duges's statement that there is a second species of _Amblystoma_, which is normal in its metamorphosis, near Mexico but at a higher alt.i.tude, which may explain Velasco's observation that regularly transforming _Amblystomas_ occur near that city; and thirdly, he made a careful examination of the two lakes, Chalco and Xochimilco, where the axolotls occur in abundance and are procured for the market. The following is an abstract of Gadow's very interesting account. "Lakes Chalco and Xochimilco are a paradise, situated about 10 ft. higher than the Texcoco Lake and separated from it by several hills. High mountains slope down to the southern sh.o.r.es, with a belt of fertile pastures, with shrubs and trees and little streams, here and there with rocks and ravines. In fact, there are thousands of inviting opportunities for newts to leave the lake if they wanted to do so. Lake Xochimilco contains powerful springs, but away from them the water appears dark and muddy, full of suspended fresh and decomposing vegetable matter, teeming with fish, larvae of insects, _Daphniae_, worms and axolotl. These breed in the beginning of February. The native fishermen know all about them; how the eggs are fastened to the water plants, how soon after the little larvae swarm about in thousands, how fast they grow, until by the month of June they are all grown into big, fat creatures ready for the market; later in the summer the axolotls are said to take to the rushes, in the autumn they become scarce, but none have ever been known to leave the water or to metamorphose, nor are any perfect _Amblystomas_ found in the vicinity of the two lakes."

In Gadow's opinion, the reason why there are only perennibranchiate axolotls in these lakes is obvious. The constant abundance of food, stable amount of water, innumerable hiding-places in the mud, under the banks, amongst the reeds and roots of the floating islands which are scattered all over them,--all these points are inducements or attractions so great that the creatures remain in their paradise and consequently retain all those larval features which are not directly connected with s.e.xual maturity.

There is nothing whatever to prevent them from leaving these lakes, but there is also nothing to induce them to do so. The same applies occasionally to European larvae, as in the case observed in the Italian Alps by F. de Filippi. Nevertheless, in the axolotl the latent tendency can still be revived, as we have seen above and as is proved by the experiments of Marie von Chauvin. When once s.e.xually ripe the axolotl are apparently incapable of changing, but their ancestral course of evolution is still latent in them, and will, if favoured by circ.u.mstances, reappear in following generations.

BIBLIOGRAPHY.--G. Cuvier, _Mem. Inst.i.t. Nation._ (1807), p. 149, and in A.

Humboldt and A. Bompland, _Observ. zool._ i. (1811), p. 93; L. Calori, _Mem. Acc. Bologna_, iii. (1851), p. 269; A. Dumeril, _Comptes rendus_, lx.

(1865), p. 765, and _N. Arch. Mus._ ii. (1866), p. 265; E. Blanchard, _Comptes rendus_, lx.x.xii. (1876), p. 716; A. Weismann, _Z. wiss. Zool._ xxv. (Suppl. 1875), p. 297; M. von Chauvin, _Z. wiss. Zool._ xxvii. (1876), p. 522; F. de Filippi, _Arch. p. la zool._ i. (1862), p. 206; G. Hahn, _Rev. Quest. Sci._ Brussels (2), i. (1892), p. 178; H. Gadow, _Nature_, lxvii. (1903), p. 330.