Spongillæ in which the gemmules are covered with layers of distinct polygonal air-spaces with chitinous walls.
The gemmules are usually fastened together in groups, which may either be free in the sponge or adhere to its support as a "pavement layer"; sometimes, however, they are not arranged in this manner, but are quite independent of one another. The skeleton is usually delicate, sometimes very stout (_e. g._, in _S. nitens_, Carter).
The term _Eunapius_ here used is not quite in the original sense, for Gray included under it Bowerbank's _Spongilla paupercula_ which is now regarded as a form of _S. lacustris_. His description, nevertheless, fits the group of species here associated except in one particular, viz., the smoothness of the gemmule-spicules to which he refers, for this character, though a feature of _S. carteri_, is not found in certain closely allied forms. The use of "_Spongilla_" in a double sense may be avoided by the adoption of Gray's name.
The subgenus _Eunapius_ is, like _Euspongilla_, cosmopolitan. It is not, however, nearly so prolific in species. Four can be recognized in India, two of which range, in slightly different forms, as far north as Europe, one of them also being found in North America, Northern Asia, and Australia.
8. Spongilla carteri* _Carter_ (_Bowerbank_, in litt.). (Plate II. fig. 1.)
_Spongilla friabilis_?, Carter (_nec_ Lamarck), J. Bombay Asiat. Soc. iii, p. 31, pl. i, fig. 3 (1849), & Ann. Nat. Hist. (2) iv, p. 83, pl. ii. fig. 3 (1849).
_Spongilla carteri_, Carter, Ann. Nat. Hist. (3) iii, p. 334, pl. viii, figs. 1-7 (1859).
_Spongilla carteri_, Bowerbank, P. Zool. Soc. London, 1863, p. 469, pl. xxxviii, fig. 20.
_Eunapius carteri_, J. E. Gray, _ibid._ 1867, p. 552.
_Spongilla carteri_, Carter, Ann. Nat. Hist. (5) vii, p. 86 (1881).
_Spongilla carteri_, _id._, _ibid._ x, p. 369 (1882).
_Spongilla carteri_, Potts, P. Ac. Philad. 1887, p. 194.
_Spongilla carteri_, Weltner, Arch. Naturg. lxi (i), pp. 117, 134 (1895).
_Spongilla carteri_, Kirkpatrick, P. Zool. Soc. London, 1906 (i), p. 219, pl. xv, figs. 3, 4 (? figs. 1, 2).
_Spongilla carteri_, Annandale, J. Asiat. Soc. Bengal, 1906, p. 188, pl. i, fig. 1.
_Spongilla carteri_, Willey, Spolia Zeyl. iv, p. 184 (1907).