REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 91 



has been found morphometrically indistinguishable, form one ex- 

 treme of the group; the species of the E. fortis group, with their 

 pronounced tendencies to ecomorphic malformations, represent the 

 other. Since little is known about the North American species E. 

 robusta and E. subdivisa, which take up a central position on this 

 grade, it seems advisable not to merge all these species with E. ramsayi 

 until additional data will be available. 



In Australia, E. ramsayi is a widely distributed species, and its 

 occurrence in New Zealand has been recorded by Schroder (1935). 

 Annandale's (1909c) record from New Guinea is still dubious, since it 

 possibly refers to a species of Radiospongilla, perhaps B. indica or 

 R. crateriformis. Material of this sponge was not available for study. 



Ephydatia robusta (Potts, 1887) 



Plate 7, figures 11, 12 



Meyenia robusta Potts, 1887, p. 225.— Kirsch, 1909, p. 37. — Pennnk, 1953, p. 93. — 



Penney, 1960, p. 53. 

 Ephydatia robusta Weltner, 1895, p. 114. — ?Garbini, 1897, p. 477. — ?Annandale, 



1907c, p. 24.— Smith, 1921, p. 17.— Arndt, 1926, p. 343.— De Laubenfels, 



1932, p. 111.— Old, 1936b, p. 11. 

 Meyenia subdivisa Potts, 1887, p. 226 (no name but description in Mills, 1884, 



p. 147).— Kirsch, 1909, p. 37.— Eshleman, 1950, p. 40.— Moore, 1951, p. 63.— 



Pennak, 1953, p. 91.— Penney, 1960, p. 54. 

 Ephydatia subdivisa Weltner, 1895, p. 114. — Smith, 1921, p. 17. — Gee, 1931e, 



p. 50; 1932c, p. 32. 



Material. — Several slides of Pott's collection (USNM), also a 

 number of slides from specimens fitting both the descriptions of 

 M. robusta and M. subdivisa (N. Gist Gee and JTP). 



Description. — Sponge, according to previous descriptions, forming 

 encrustations to massive growths; additional data on surface, oscula, 

 and consistency not reliably recorded. 



Megascleres slightly curved and moderately stout amphioxea, 

 ranging from cylindrical to subfusiform, armed with inconspicuous 

 spines except at theu* tips, exceptionally entirely smooth; length 

 range 230-330 fx, width range 12-17 m- 



Microscleres absent. 



Gemmoscleres birotulates of one class, mth stout cylindrical 

 shafts, typically with a number of acute and prominent spines, 

 rarely smooth; and terminally with rotules of equal diameter and 

 distinctly flat shape, irregularly incised in a number of lobes and 

 rays; malformations frequent, outer surface of rotules often gi'anulated, 

 spines on shaft forked or subdivided, rotules abnormally developed; 

 length of shaft typically 45-50 n, diameter of rotules 20-22 n, width of 

 shaft 6-7 n. 



279-430—68 7 



