REVISION OF FRESHWATER SPONGES OF SPONGILLIDAE 113 



originally described by Potts (1880a) under the name of Spongilla 

 tentasperma. Although a few pages later Potts redescribed the same 

 species under the name of S. tenosperma and thus aided the retention 

 of this specific name by most subsequent authors, S. tentasperma 

 certainly has page priority and therefore represents the correct 

 specific name of the spongUlid discussed. 



The spicules of H. tentasperma closely resemble those of H. latitenta 

 in general structure, but the peculiar burlLke "rotules" together with 

 the entu-ely different shape, length, and armature of the gemmular 

 porous tube in the former species are sufficient criteria to separate it 

 readily from the latter. However, additional material and data are 

 desirable in order to assess possible evironmental factors leading to 

 the often freak condition of the gemmoscleres in H. tentasperma, 

 which could well point to a greater relationship to H. latitenta than 

 hitherto demonstrated. 



Heteromeyenia tubisperma (Potts, 1881) 



Plate 9, figures 5-7, 17 



Carterella tubisperma Potts, 1881a, p. 150. — Mills, 1882, p. 57. 



Carterius tubisperma Mills, 1887, p. 162. — Potts, 1887, p. 263.— Kellicott, 1891, 



p. 103.— Weltner, 1895, p. 114.— Kirsch, 1909, p. 37.— Smith, 1921, p. 17.— 



Old, 1932b, p. 471; 1936b, p. 11.— Arndt, 1926, p. 344.— De Laubenfels, 



1932, p. 111.— Eshleman, 1950, p. 44. 

 Heteromeyenia tubisperma Schroder, 1927b, p. 108. — Gee, 1931e, p. 51; 1932c, p. 25; 



1937, p. 285. 

 Carterius tubispermus Wurtz, 1950, p. 7. — Pennej'^, 1960, p. 34. 



Material. — Slides of specimen from Canada (N. Gist Gee) . 



Description. — Sponge, according to previous descriptions, forming 

 irregularly massive encrustations on solid objects; surface uneven to 

 slightly papillose, oscula inconspicuous. Skeleton forming an irregular 

 network of spicule fibers, amount of spongin apparently not yet re- 

 corded. Consistency of live sponge soft, texture loose. 



Megascleres sparsely microspined fusiform amphioxea, slender and 

 sharply pointed; length range 190-230 fx, width range 7-10 fx. 



Microscleres slender and rather long amphioxea, entirely spined, 

 spines in central portion of sclere distinctly larger; length range 85- 

 90 fi, width range 2-3 n. 



Gemmoscleres birotulates of two length groups, usually possessing 

 identical rotules in both classes; shafts of both cylindrical and stout, 

 armed with few acute spines, occasionally entirely smooth; rotules of 

 equal diameter, markedly umbonate, at their lateral margins with 

 nimierous deeply cleft and distinctly recurved teeth; length range of 

 longer class 60-70 n, of shorter 40-48 m; diameter of rotules 18-19 m- 



Gemmules numerous in mature sponge, ranging in diameter 500-550 

 At, spherical; pneumatic layer well developed, consisting of minute 



