Extinct Birds Part 25

PLOTUS Na.n.u.s NEWT. & GAD.

_Plotus na.n.u.s_ Newton and Gadow, Trans. Zool. Soc. XIII p. 288, pl.

x.x.xIV figs 1-5. (1893).

The humerus, the pelvis with sacrum, and the tibia were the materials on which our authors founded this new species. They state that all the strongly developed characters in these bones leave no possible doubt as to its being a species of _Plotus_, and its diminutive size at once distinguishes it from the three known species--_P. anhinga_, _P.

melanogaster_, and _P. novaehollandiae_.

The measurements are as follows:--

Left humerus, length 89 mm.

Left tibia, length 61 "

Distance from acetabular axis to anterior end of sacrum 30 mm.

Distance between ventral inner margins of the acetabula 14.5 mm.

Habitat: Mauritius. (Also recorded from Madagascar.)

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"CHENOPIS SUMNERENSIS" FORBES.

_Chenopis sumnerensis_ Forbes, Trans. N.Z. Inst. XXIV, p. 188 (1892) (Nomen nudum).

This appears to have been a very large species, with not very great powers of flight, if not flightless.

Habitat: New Zealand and Chatham Islands.

Bones from Chatham Islands in my collection.

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CHENALOPEX SIRABENSIS ANDREWS.

_Chenalopex sirabensis_ Andrews, Ibis 1897, p. 355, pl. IX, figs. 1-3.

This species of which skull, sternum, pelvis, the bones of fore and hind limbs, &c., are preserved, appears to be closely allied to _Chenalopex aegyptiacus_, but has such a number of small differences that Mr. Andrews is, I think, quite justified in separating it; I do not, however, agree with him when he suggests that perhaps it is the same as Newton and Gadow's _Sarcidiornis mauritia.n.u.s_, although many of the bones agree. Of course, his line of comparison was strengthened by the fact of subfossil bones of _Plotus na.n.u.s_ occurring both in Mauritius and Madagascar; but it does not follow that because in one family of birds the same species occurred in two places the others must do likewise, and, therefore, one must not necessarily regard a certain similarity of osteological characters as proof of ident.i.ty. I must here again refer my readers to Mr. Andrews' very full description.

Habitat: Sirabe in C. Madagascar.

The measurements are:--

Coracoid 67-75 mm.

Humerus 132-147 "

Radius 126-134 "

Ulna 129-142 "

Metacarpus 76-85 "

The smaller bones, undoubtedly, belonged to female, and the larger to male individuals.

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CENTRORNIS ANDREWS.

Allied to _Chenalopex_ and _Chenopis_, but differs from _Chenalopex_ in the form and proportion of its metatarsus, and from all other Anserine forms by the extreme length and slenderness of the shaft of the tibio-tarsus and the relative shortness of the fibular crest. From _Chenopis_ it differs in several respects, and the very long fibular crest of the latter at once separates them.

CENTRORNIS MAJORI ANDREWS.

_Centrornis majori_ Andrews, Ibis 1897, p. 344, pl. VIII.

This species was discovered by Dr. Forsyth Major and Monsieur Robert in the bed of an old lake at Sirabe, Central Madagascar, in 1896-1897. It was similar in many respects to _Sarcidiornis_ and _Chenalopex_ but differed in its large size and the great length of its legs. Indeed, judging from the slenderness of the metatarsus and femur and the slight degree of inflection of the lower end of the long tibia, it seems probable that this bird was ill adapted for swimming, though a good runner. The wings were long and powerful and armed with a long spur. I must refer my readers for a fuller description to Mr. Andrews, as quoted above.

The measurements are:--

_Tibia._

Length (exclusive of cnemial crest) 213-215 mm.

Width of upper articular surface 20-21 "

Width of middle of shaft 11-11.5 "

Thickness of shaft 8.5-9 "

Width of distal extremity 20-21 "

_Femur._

Length 103-107 mm.

Width of proximal extremity 25-26 "

Width of distal extremity 26 "

Width of shaft 11 "

{96} _Metatarsus._

Length 130 mm. approx.

Width of shaft 8.5 "

Width of middle trochlea 10 "

_Coracoid._

Length 31 mm.

Width of glenoidal surface 13 "