REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 17 



knoblike inflations at their tips; length range 75-124 fx, width range 

 2-3 M. 



Gemmoscleres slender and almost cylindrical amphistrongyla, 

 occasionally amphioxea, feebly curved, covered with large and always 

 recurved spines; these often more numerous at the tips of the scleres, 

 where they sometimes form several ringlike aggregations; length 

 range 78-130 n, width range 5-10 /x- 



Gemmules very abundant in sponge, scattered throughout its body, 

 usually large and spherical, ranging 450-600 fj, in diameter; pneumatic 

 layer only moderately thick, distinctly granular; gemmoscleres em- 

 bedded in this layer rather sparsely and at irregular angles, their tips 

 usually projecting beyond outer surface of layer; foramen never tubu- 

 lar, though slightly elevated, and often bearing a shallow peripheral 

 collar. 



Distribution. — Formerly known only from India, SE. Asia, and 

 Africa; the present studies were able to extend the known range of this 

 species to Australia and South America. 



Color in life. — Pale gray to off white. 



Discussion. — S'. alba possesses, in contrast to S. lacustris, a quite 

 pronounced uniformity in the structure of its spicular components, and 

 it is difficult to understand why Annandale (1906, 1907, 1909, 1915, 

 1919) found it necessary to express some few and immaterial varia- 

 tions in establishing as many as three separate species, as well as three 

 "varieties" of this sponge. With this large number of supposedly 

 differing forms, erected by a known specialist like Annandale, S. alba 

 subsequently became a rather obscure species, and fiu-ther confusion 

 was added in later work, considering even the S. cerebellata Bowerbank 

 group of sponges as varietal forms of S. alba. 



A close examination of all the species and "varieties" listed above as 

 sjmonyms revealed clearly that their differing structural character of 

 spicules are all well within the usual range of typical scleres found in 

 S. alba. Annandale's three "varieties," with respect to their spicular 

 components, display nothing more than ecomorphic alterations caused 

 by a differing chemical and physical environment. S. nana and 

 particularly S. microsclerifera cannot be mistaken for any species other 

 than S. alba, and merely represent a stunted mode of growth due to 

 environmental factors. S. travancorica was established by Annandale 

 (1909f) chiefly by one apparently typical criterion, i.e., the grouping 

 of gemmules near the base of the sponge. Apart from the fact that the 

 spicular components of both S. alba and S. travancorica assessed from 

 the type material examined are almost indistinguishable, the peculiar 

 arrangement of the gemmules in the latter can be fully explained by 

 the flat growth of Annandale's type specimens of S. travancorica. 



