112 U.S. NATIONAL MUSEUM BULLETIN 2 72 



typical structure of the cirrous foraminal appendages on the gem- 

 mules of H. latitenta, the gemmoscleres too are sufficiently different 

 from those of any of its congeners to warrant the separate specific 

 status of this species. 



Heteromeyenia tentasperma (Potts, 1880) 



Plate 9, figures 8, 9, 18 



Spongilla tentasperma Potts, 1880a, p. 331. 

 Spongilla tenosperma Potts, 1880b, p. 356. 

 Carterella tenosperma Potts, 1881a, p. 149. 

 Carterius tenosperma Potts, 1887, p. 245. — Kellicott, 1891, p. 104. — Weltiier, 1895, 



p. 114.— Kirsch, 1909, p. 38.— Smith, 1921, p. 17.— Old, 1936b, p. 11.— Jewell, 



1939, p. 11. 

 Heteromeyenia tenosperma Schroder, 1927b, p. 108. — Gee, 1931e, p. 51; 1932c, p. 34. 

 Carterius tentaspermus Wurtz, 1950, p. 6. — Penney, 1960, p. 34. 

 Carterius tentasperma Jewell, 1952, p. 452. 



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



Description. — Sponge, according to original descriptions, forming 

 UTCgular masses on aquatic plants or shallow cushions on rocks; 

 surface comparatively even but hispid, oscula inconspicuous. Skeleton 

 forming an irregular network of spicule fibers, joined together by a 

 small amount of spongin. Consistency of live sponge not reliably 

 recorded. 



Megascleres sparsely microspined fusiform amphioxea, very slender 

 and sharply pointed; length range 260-280 n, width range 7-10 /i. 



Microscleres more or less uniformly spined slender amphioxea; 

 length range 75-80 p. width range 2-3 ix. 



Gemmoscleres of two length groups, usually possessing identical 

 rotules; shafts of both stout and cylindrical, armed with a smaller 

 number of acute spines; rotules represented by a burlike arrangement 

 of lateral spines, often penetrated by a prolongation of the shaft; 

 length range of longer class 65-72 n of shorter 50-55 /x; diameter of 

 rotules 15-18 fi. 



Gemmules numerous in mature sponge, ranging in diameter 

 420-450 n, spherical; pneumatic layer well developed, consisting of 

 minute subspherical air spaces; shorter gemmoscleres entirely con- 

 tained within this layer, the few longer often projecting slightly 

 beyond outer gemmular membrane; foramen distinctly tubular, porus 

 tube comparatively short and conical, bearing three to six irregular 

 and long cirrous projections. 



Distribution. — Found only in northeastern parts of the United 

 States. 



Color in life. — Kecorded as yellowish green. 



Discussion. — This species, although listed by the majority of 

 authors as Carterius tenospermus or Heteromeyenia tenosperma, was 



