[Illustration: Fig. 19.--Spicules of _Spongilla ultima_ (from type specimen), × 120.]
_Gemmules_ adherent, spherical, large, each covered by two distinct layers of horizontal spicules; the outer layer intermixed with skeleton-spicules and often containing relatively large siliceous spheres, a large proportion of the spicules being irregular in shape; the spicules of the inner layer much more regular and as a rule sausage-shaped. The outer layer is contained in a chitinous membrane which spreads out over the base of the sponge. The foraminal tubules are short and straight.
This sponge is allied to _S. bombayensis_, from which it is distinguished not only by the abnormal characters of its gemmule-spicules and the absence of flesh-spicules, but also by the form of its skeleton-spicules and the structure of its skeleton. I have examined several specimens dry and in spirit; but _S. ultima_ is the only Indian freshwater sponge, except _Corvospongilla burmanica_, I have not seen in a fresh condition.
TYPES in the Indian Museum; co-types at Trivandrum.
HABITAT. Discovered by Mr. R. Shunkara Narayana Pillay, of the Trivandrum Museum, in a tank near Cape Comorin, the southernmost point of the Indian Peninsula.
_Pectispongilla_, Annandale, Rec. Ind. Mus. iii, p. 103 (1909).
The structure of the sponge resembling that of _Euspongilla_ or _Ephydatia_; but the gemmule-spicules bear at either end, at one side only, a double vertical row of spines, so that they appear when viewed in profile like a couple of combs joined together by a smooth bar.
[Illustration: Fig. 20.--Gemmule and spicules of _Pectispongilla aurea_ (type specimen). _a_, Skeleton-spicules; _b_, gemmule-spicules; _b'_, a single gemmule-spicule more highly magnified.]
GEOGRAPHICAL DISTRIBUTION.--The genus is monotypic and is only known from Travancore and Cochin in the south-west of the Indian Peninsula.
_Pectispongilla aurea_, Annandale, _op. cit._, p. 103, pl. xii, fig. 2.
_Sponge_ forming minute, soft, cushion-like masses of a deep golden colour (dull yellow in spirit); the surface smooth, minutely hispid. One relatively large depressed osculum usually present in each sponge; pores inconspicuous; dermal membrane in close contact with the parenchyma.