Freshwater Sponges, Hydroids & Polyzoa Part 47

_Zooecia._ The zooecia are short and slender, erect or nearly so, distinctly emarginate and furrowed. Their ectocyst is soft, colourless and transparent but minutely roughened on the surface.

_Polypide._ The tentacles number from 30 to 35 and are rather short and stout, sometimes being slightly expanded at the tips. The stomach is comparatively short and abruptly truncated posteriorly.

_Statoblasts._ Both free and fixed statoblasts are found, and both are variable in form, the latter varying in outline from the circular to the broadly oval. The free statoblasts resemble those of _Plumatella punctata_, but are sometimes rather more elongate.

TYPE in the Indian Museum.

[Ill.u.s.tration: Fig. 45.--Zoarium of _Stolella indica_ on stem of water-plant (from Calcutta), 6.]

GEOGRAPHICAL DISTRIBUTION.--So far as we know, this species is confined to the Indo-Gangetic Plain. Major Walton found it at Bulandshahr in the United Provinces, and it is not uncommon in the neighbourhood of Calcutta.

BIOLOGY.--The zoaria of _S. indica_ are usually fixed to the roots of duckweed or to the stems of other plants. They are often found together with those of _P. punctata_. A slight infusion of brackish water into the ponds in which it lives does not seem to be inimical to this species, but I have found it in ponds in which nothing of the kind was possible. It flourishes during the "rains" and, to judge from specimens kept in an aquarium, is very short-lived. Major Walton found it growing over a zoarium of _Hislopia lacustris_.

Subfamily B. LOPHOPINae.

The zoaria of this subfamily are never dendritic but form gelatinous ma.s.ses which, except in _Australella_, are cushion-shaped or sack-like.

With the possible exception of _Australella_, they possess to a limited extent the power of moving along vertical or horizontal surfaces, but it is by no means clear how they do so (see p. 172). The statoblasts are remarkable for their large size, and it is noteworthy that _Australella_, which is intermediate in structure between the Plumatellinae and the Lophopinae, possesses statoblasts of intermediate size. The swim-ring is always well developed, and fixed statoblasts are unknown.

Only two genera (_Lophopodella_ and _Pectinatella_) have been definitely proved to occur in India, but a third (_Lophopus_[BK]) is stated to have been found in Madras. Should it be met with it will easily be recognized by the upright position of its polypides when their tentacles are expanded and by the fact that the statoblasts never bear marginal processes.

[Footnote BK: Only two species are known, _L. crystallinus_ (Pallas) from Europe and N. America, with oval statoblasts that are produced and pointed at the two ends, and _L.

jheringi_, Meissner from Brazil, with irregularly polygonal or nearly circular statoblasts.]

Genus 3. LOPHOPODELLA, _Rousselet_.

_Lophopodella_, Rousselet, Journ. Quek. Micr. Club (2) ix, p. 45 (1904).

_Lophopodella_, Annandale, Rec. Ind. Mus. v, p. 54 (1910).

TYPE, _Pectinatella carteri_, Hyatt.

_Zoarium._ The zoarium consists of a circular or oval ma.s.s of no great size. Polyparia do not form compound colonies.

_Polypides._ The polypides lie semi-rec.u.mbent in the ma.s.s and never stand upright in a vertical position.

_Statoblasts._ The statoblasts are of considerable size and normally bear at both ends a series of chitinous processes armed with double rows of small curved spinules.

As a rule the genus is easily recognized by means of the statoblasts, but sometimes the processes at the ends of these structures are absent or abortive and it is then difficult to distinguish them from those of _Lophopus_. There is, however, no species of that genus known that has statoblasts shaped like those of the Indian species of _Lophopodella_.

Three species of _Lophopodella_, all of which occur in Africa, have been described; _L. capensis_ from S. Africa, which has the ends of the statoblast greatly produced, _L. thomasi_ from Rhodesia, in which they are distinctly concave, and _L. carteri_ from E. Africa, India and j.a.pan, in which they are convex or truncate.

The germination of the gemmule and the early stages in the development of the polyparium of _L. capensis_ have been described by Miss Sollas (Ann. Nat. Hist. (8) ii, p. 264, 1908).

37. Lophopodella carteri (_Hyatt_). (Plate III, figs. 4, 4_a_.)

_Lophopus_ sp., Carter, Ann. Nat. Hist. (3) iii, p. 335, pl.

viii, figs. 8-15 (1859).

? _Lophopus_ sp., Mitch.e.l.l, Q. J. Micr. Sci. London (3) ii, p. 61 (1862).

_Pectinatella carteri_, Hyatt, Comm. Ess.e.x Inst. iv, p. 203 (footnote) (1866).

_Pectinatella carteri_, Meissner, Die Moosthiere Ost-Afrikas, p. 4 (in Mobius's Deutsch-Ost-Afrika, iv, 1898).

_Lophopodella carteri_, Rousselet, Journ. Quek. Micr. Club, (2) ix, p. 47, pl. iii, figs. 6, 7 (1904).

_Lophopus carteri_, Annandale, Rec. Ind. Mus. ii, p. 171, fig. 3 (1908).

_Lophopodella carteri_, _id._, _ibid._ v, p. 55 (1910).

_Zoarium._ The zoarium as a rule has one horizontal axis longer than the other so that it a.s.sumes an oval form when the polypides are expanded; when they are retracted its outline is distinctly lobular. Viewed from the side it is mound-shaped. The polypides radiate, as a rule in several circles, from a common centre. The ectocyst is much swollen, hyaline and colourless.

_Polypide._ The polypide has normally about 60 tentacles, the velum at the base of which is narrow and by no means strongly festooned. The stomach is yellow or greenish in colour. The extended part of the polypide measures when fully expanded rather less than 3 mm., and each limb of the lophoph.o.r.e about the same.

_Statoblast._ The statoblast is variable in shape and size but measures on an average about 0.85 0.56 mm. The ends are truncate or subtruncate; the capsule is small as compared with the swim-ring and as a rule circular or nearly so. The processes at the two ends are variable in number; so also are their spinules, which are arranged in two parallel rows, one row on each side of the process, and are neither very numerous nor set close together; as a rule they curve round through the greater part of a circle and are absent from the basal part of the process.

[Ill.u.s.tration: Fig. 46.--Lophopodella carteri (from Igatpuri Lake).

A=outline of a zoarium with the polypides expanded, as seen from below through gla.s.s to which it was attached, 4; B=outline of a zoarium with the polypides highly contracted, as seen from above, 4; C=statoblast, 75.]

37 _a._ Var. himalayana.

_Lophopus lendenfeldi_, Annandale (_nec_ Ridley), J. As.

Soc. Bengal, (n. s.) iii, 1907, p. 92, pl. ii, figs. 1-4 (1907).

_Lophopus lendenfeldi_ var. _himalaya.n.u.s_, _id._, Rec. Ind.

Mus. i, p. 147, figs. 1, 2 (1907).

_Lophopus himalaya.n.u.s_, _id._, _ibid._ ii, p. 172, fig. 4 (1908).

This variety differs from the typical form in having fewer tentacles and in the fact that the marginal processes of the statoblast are abortive or absent.

_Pectinatella davenporti_, Oka[BL] from j.a.pan is evidently a local race of _L. carteri_, from the typical form of which it differs in having the marginal processes of the statoblast more numerous and better developed.

The abortive structure of these processes in var. _himalayana_ points to an arrest of development, for they are the last part of the statoblast to be formed.

[Footnote BL: Zool. Anz. x.x.xi, p. 716 (1907), and Annot.

Zool. j.a.pon. vi, p. 117 (1907).]

TYPES. The statoblasts mounted in Canada balsam by Carter and now in the British Museum must be regarded as the types of the species named but not seen by Hyatt. The types of the var. _himalayana_ are in the Indian Museum and those of the subspecies _davenporti_ presumably in the possession of Dr. Oka in Tokyo.

GEOGRAPHICAL DISTRIBUTION.--The typical form occurs in Bombay, the W.

Himalayas and possibly Madras, and its statoblasts have been found in E.

Africa; the var. _himalayana_ has only been taken in the W. Himalayas and the subspecies _davenporti_ in j.a.pan. Indian localities are:--BOMBAY PRESIDENCY, Igatpuri Lake, W. Ghats (alt. _ca._ 2,000 feet); the Island of Bombay (_Carter_): W. HIMALAYAS, Bhim Tal, k.u.maon (alt. 4,500 feet).