SILICIOUS AND HORNY SPONGES WILSON. 303 



v 



Sollas (1888, p. 241) to Erylus. S. intermedia has (dermal ?) 

 granulated microxeas 75 y, long. 



Caminus O. Schmidt (1862, p. 48). —Sollas (1888, p. 214).— Part 

 Lendenfeld (1903, p. 92). 



With afferent chone canals, the roofs of which are cribriporal, 

 and ordinary oscula of good size. The magasclere-complex includes 

 orthotriaenes and rhabds, but lacks anatriaenes and protriaenes. 

 The sterrasters are spheroidal or ellipsoidal, somewhat flattened in 

 some species. The other microscleres are spherules which form a 

 dermal layer, and in some species euasters which do not appear at 

 the surface. 



As Topsent (1911, p. 3) remarks, Lendenfeld in his Tetraxonia 

 (1903, p. 92) destroys the homogeneity of Caminus by altering the 

 diagnosis so as to include Geodia megastrella Carter, in which the 

 dermal (somal in Sollas' terminology) microsclere is a euaster and 

 not a spherule. 



In 1910 (p. 221) Lendenfeld gives a definition of Caminus in which 

 he says " the dermal microscleres are asters." But this is equivalent 

 to wiping out the useful distinction between asters and spherules, a 

 distinction which is actual even if we admit that spherules are phy- 

 logenetically derived from asters. 



Isops Sollas (1880, p. 396).— Sollas (1888, p. 236).— Lendenfeld 

 (1903, p. 93). 



Skeleton as in Geodia, and in habitus and arrangement of orifices 

 not distinguishable from Geodia. Incurrent and excurrent cortical 

 canals, both, uniporal chone canals. 



In the case of many of the older species enrolled here (Sollas, 

 1880, Lendenfeld, 1903), it must be understood that the assignment 

 to Isops is somewhat provisional, depending on the assumption that 

 the apertures scattered over the surface are the openings of chone 

 canals. 



Since Lendenf eld's Tetraxonia, species have been described by 

 Topsent (1906 b, p. 13) ; Lendenfeld (1906, pp. 315, 317, 319) ; Hent- 

 schel (1909, p. 365), /. membranacea, referred to Aurora by Dendy 

 (1916, p. 243). 



Caminella Lendenfeld (1894, p. 62 ) .—Lendenf eld (1903, p. 89). 



In skeleton similar to Geodia. With incurrent uniporal chone 

 canals. Instead of excurrent chone canals, there are efferent canals 

 and oscula of the ordinary tetraxonid type. 



The genus embodies a definite idea, departing from Isops in the 

 character of its excurrent canals. 



In Lendenf eld's later definition of the genus (1903) he restricts 

 his statement, as in the case of the other genera of this family, to the 

 excurrent and incurrent orifices, without mentioning the chone canals, 

 whereas the presence or absence of the latter, and the variety of de- 



