SILICIOUS AND HORNY SPONGES WILSON. 329 



choanosome. Total length 12-20 u, commonly about 16 \>.. Spicule 

 varies in details of shape. 



Holotype.— Cat No. 21252, U.S.N.M. 



Dendy has raised the question (19165, p. 99) whether this Avidely 

 distributed species is indeed really a species or only a collec- 

 tion of forms which happen to agree in spiculation, because in 

 different localities related sponges (possibly species of Ancorina) 

 have undergone a similar reduction of skeleton. The same reflec- 

 tion is appropriate to many others of our literature species. A first 

 essential to the answer is a detailed, intimate, knowledge of the struc- 

 ture and development as observed in different localities. A part of 

 the value of systematic zoology, as it seems to me, is to indicate 

 critical cases which are well worth such intensive study. 



Genus JASPIS Gray (1867). 



Jaspis Gray, 1867, p. 526, plus Coppatias Sollas, 18SS, p. 206, plus Dory- 

 pier es Sollas, 1888, p. 426, plus Rhabdastrella Thiele, 1903, p. 934. 



With diactinal (oxeate) megascleres. Microscleres are euasters. 

 The body may be lamellate or cyathiform, or a cake-shaped mass, 

 or massive and variously shaped, or incrusting. The oscula are 

 small, numerous, and scattered; the pores and oscula in some forms 

 on opposite faces. The megascleres are intercrossed in all direc- 

 tions without order (Jaspis, Dorypleres), or arranged partly in 

 radiating fibers, partly scattered (Coppatias). In some species the 

 megascleres of the ectosome are smaller than those of the choano- 

 some, and are sometimes designated microxeas. They lie in a pre- 

 dominantly tangential direction and may constitute a well marked 

 ectosomal skeleton. The microscleres are especially abundant at the 

 surface. 



Topsent (1898, p. 107) pointed out that Dorypleres Sollas could 

 not be distinguished from Coppatias Sollas. 



Lindgren (1898, p. 357) and Thiele (1900, p. 58) would retain 

 Jaspis Gray (syn. Dorypleres Sollas) for forms in which the 

 megascleres are scattered without order and Coppatias Sollas for 

 those in which they are combined, partially at least, in tracts. 

 Topsent (1904, p. 128) would also follow this practice. But the 

 distinction made between these two groups of species is scarcely prac- 

 ticable, and of the two names Dendy (1916, p. 252) shows that the 

 rules of nomenclature demand Jaspis for the combined group of 

 forms. 



Thiele (1903, p. 934) handles the generic idea, suggesting subdivi- 

 sion of the genus. Nomenclature demands, he thinks, that Coppatias 

 be merged in Jaspis. The species without small oxeas and with 

 radial tracts of oxeas should be combined in a new genus Rhahdas- 

 81709—25 5 



