148 U-S- NATIONAL MUSEUM BULLETIN 272 



free microscleres in the form of spined amphioxea, and whose gemmiiles 

 lack an external arrangement of typically birotulate gemmoscleres. 

 Following the present studies, the genus Tuhella Carter cannot be 

 retained in spongillid taxonomy since it represents a heterogeneous 

 grouping of species now known to belong to Metania Gray, Trocho- 

 spongilla Vejdovsky, and even Heterorotula, new genus. 



The presence of free microscleres, although previously not recorded 

 for M. vesparia (von Martens) and M. vesparoides (Annandale), has 

 now been established for all Metania species alike. The present 

 studies furthermore revealed that the two species formerly known as 

 Tubella pottsi Weltner and Metania lissostrongyla Burton are identical, 

 and that both display no criteria of importance to justify even racial 

 differences between them and M. vesparia. 



Of other species, unfortunately not available in the material studied, 

 M. spinata (Carter) certainly belongs here and possibly also M. 

 thumii (Traxler), known only from subfossil deposits. Tuhella anon- 

 yma (Carter) is insufficiently described and most probably belongs 

 to a different genus (Gee, 1933c). 



The identity of M. rhodesiana Burton and M. innominata Burton 

 has yet to be resolved. Although present in the material for this 

 study, the slides of these two species appear to be a mixture of spicular 

 components of several species. M. rhodesiana is generically indeter- 

 minable, since gemmules and gemmoscleres are absent, and the 

 growth of the sponge as well as the structure of its megascleres are 

 quite atypical for Metania. M. innominata on the other hand pos- 

 sesses typical gemmules and gemmoscleres of this genus, which 

 Burton admits to be practically identical with those of AI. lissostron- 

 gyla, but its megascleres are fusiform amphioxea. Since the free 

 microscleres in both M. innominata and AI. rhodesiana are described 

 by Burton as almost identical with those of the insufBciently known 

 Spongilla brieni Burton, it is impossible to deal with this complex 

 until additional material will be available. 



Metania reticulata (Bowerbank, 1863) 



Plate 14, figures 1-4 



Spongilla reticulata Bowerbank, 1863, p. 455. 

 Metania reticulata Gray, 1867, p. 551. — Penney, 1960, p. 46. 

 Tubella reticulata Carter, 1881a, p. 97. — Potts, 1887, p. 249. — Weltner, 1895, 

 p. 114.— Gee, 1931e, p. 47; 1932c, p. 43; 1933c, p. 243. 



Material.— Slides of the type (BM). 



Description.- — Sponge, according to Bowerbank (1863), forming a 

 nodulose growth on a submerged branch; surface kregularly tuber- 

 cular, oscula inconspicuous. Skeleton a coarse but rigid spicular net- 



