116 U.S. NATIONAL MUSEUM BULLETIN 272 



class; and A. biceps, although at present not readily comparable with 

 any congener, is better to be considered a dubious species until 

 additional material becomes available. 



Anheteromeyenia argyrosperma (Potts, 1880) 



Plate 10, figures 8-10 



Spongilla argyrosperma Potts, 1880b, p. 357. 



Heteromeyenia argyrosperma Potts, 1881a, p. 150; 1884b, p. 216; 1887, p. 239. — 

 MacKay, 1885, p. 233; 1889, p. 93.— Weltner, 1895, p. 114.— Smith, 1921, 

 p, i7._Gee, 1931e, p. 32; 1937, p. 285.— Old, 1932c, p. 239; 1936b, p. 11.— 

 Jewell, 1939, p. 20; 1952, p. 452.— Eshleman, 1950, p. 42.— Penney, 1956, 

 p. 43; 1960, p. 40. 



Heteromeyenia (Anheteromeyenia) argyrosperma Schroder, 1927b, p. 108. 



Heteromeyenia argyrosperma var. tenuis Potts, 1887, p. 240. — Gee, 1931e, p. 51; 

 1932c, p. 32.— Penney, 1960, p. 41. 



Heteromeyenia (Anheteromeyenia) argyrosperma var . tenuis Schroder, 1927b, p. 108. 



Material. — Numerous specimens from the United States and 

 Canada. 



Description. — Sponge, according to previous descriptions, forming 

 small to minute cushions on solid objects; surface slightly hispid but 

 otherwise even, oscula inconspicuous. Skeleton forming an irregular 

 network, joined together by a small amount of spongin. Consistency 

 of live sponge soft, texture loose. 



Megascleres slender, subfusiform to cylindrical, abruptly pointed 

 amphioxea, sparsely covered with small but sharply pointed spines; 

 length range 240-280 n, width range 13-17 /x. 



Microscleres absent. 



Gemmoscleres birotulates of two distinct length groups, in shape 

 only slightly differing from each other; the longer class w^th rather 

 robust and irregularly cylindrical shafts, often bent, and bearing 

 occasional recurved spines, and terminally with a smaller number of 

 strongly recurved, clawlike hooks; the smaller class considerably 

 shorter, their cylindrical shafts abundantly spined, their terminal 

 rotules, consisting of strongly recurved hooks, somewhat flatter than 

 in the longer series; length range of longer class 110-125 /x, width 

 range 7-10 /x) length range of smaller class 65-80 n, width range 

 6-8 n. 



Gemmules abundant in mature sponge, ranging in diameter 400- 

 450 n; pneumatic layer well developed and granular, consisting of 

 minute subspherical air spaces; gemmoscleres embedded in this layer 

 strictly radially, the shorter series not reaching to outer gemmular 

 membrane, the longer considerably surpassing it; foramen distinctly 

 tubular, porus tube slender and decreasing in width towards its apex; 

 marginal cirri absent. 



