SILICIOUS AND HORNY SPONGES WILSON. 379 



In regard to the absence of sigmas. the feature on which Lenden- 

 f eld's Tethyopsillidae (1903, p. 29, deleted by Lendenfeld, 1906) and 

 Tethyopsilla Lendenfeld (1903, p. 30) chiefly rest, it may be said that 

 Sollas, 1888 (p. 55), looks on this character as a good specific dif- 

 ference. Topsent, 1904 (p. 99), would not assign to the feature even 

 this value, and accordingly regards the specimens designated Craniella 

 zetlandica (Carter) by Sollas as not separable from Craniella 

 cranium (see Lendenfeld, 1906, p. 121). In the classification adopted 

 in this report, Tethyopsilla Lendenfeld is not accepted, but the ab- 

 sence of sigmas is looked on as a specific difference, one that dis- 

 tinguishes for instance C. simillima from the Ceylon sponges desig- 

 nated Craniella elegans by Dendy (1905, p. 95). 



The Albatross specimens of C. simillima are larger than have been 

 recorded. One is ellipsoidal, 65 mm. high, 45 mm. wide. Another is 

 spheroidal, 53 mm. in diameter. In the former there is a single 

 terminal small osculum, in the latter four small oscula near the upper 

 pole. The conules are sharp, 1-2 mm. high, frequently connected by 

 ridges and often about 2 mm. apart. Papillae of the basal surface, 

 very small, closely set elevations, appearing rounded to the eye. 

 Sponge is heavy and compact, reddish-brown at the surface, lighter 

 colored inside. One specimen is full of large bluish embryos, about 

 1,400 [x in diameter, in which the radial skeletal bundles have already 

 formed. 



The dermal membrane between the conules is riddled with pores 

 which extend up on the conules. From these, short cylindrical pore 

 canals, 20-60 \i in diameter, pass into the subdermal spaces of the 

 outer ectosomal layer. The outer layer of the ectosome is commonlv 

 200-500 [jl thick between the conules, thicker than this where the con- 

 ules are close together; nonfibrous, brownish, but without coarsely 

 granular conspicuous cells. The inner or cortical layer of the ecto- 

 some is 1,200-1,800 [/. thick, without pigment, fibrous, and is filled 

 with the radial cortical spicules which often protrude into the outer 

 estosomal layer and even reach the surface. In the extreme basal 

 region of the sponge the whole ectosome is thicken than elsewhere. 



The radial skeletal bundles coming from the center of the sponge 

 pass in the usual way into and project from the conules, some of the 

 spicules projecting several millimeters beyond the surface. The pro- 

 truding spicules include protriaenes, anatriaenes, and some large 

 oxeas, the bundles themselves being made up of these three classes of 

 spicules. 



The radial oxeas reach a size of 4 mm. by 50 [x. 



The cortical oxeas measure 1,200-1,400 by 32-50 \l. Sollas says 

 they are fusiform. I find them slightly inequiended, the inner end 

 as usual being the finer one. 



