224 



The new species differs from others of the genus not only in 

 its -remarkable shape, but also in the absence of discohexas'ters- 

 'J hese spicules occur in all other species of Cratcromorpha, and in 

 all the genera of Rosscllinae except Bathydorus. It does not seem 

 necessary, however^ to establish a new genus to include the new 

 species. 



Owing to the hypogastral membrane of C- lankesteri being con- 

 tinuous, the inner surface of the cup-wall does not present the 

 cavernous aspect usually seen in species of Cratcromorpha- 



The hard-felt-like texture of the stalk partly arises from the 

 absence of synapticulae, which, in some species, C. meycri for in- 

 stance, weld the lower end of the stalk into a compact mass of 

 stony hardness.* 



Family TetillidSB. 



Genus Spongocardium, gen. nov. 



TetilUdae free, ellipsoidal, with a poraL vestibule at one end and 

 an oscular cloaca at or near the other end of the long diameter of 

 the upper surface. 



Spongocardium gilchristi, sp. n. 

 Plate II, figs. 1, lA, and Plate III, fig. 1. 



Sponge with the upper surface somewhat flattened, and the 

 lower surface deeply convex- 



Poral vestibule usually with a spicular fringe, and oscular 

 cloaca usually with a sharp cut edge without fringe. Surface of 

 poral vestibule smooth and uniform; surface of oscular cloaca 

 reticulate, with oscules (.25 — .5 mm. in diameter) in the meshes 

 of the network. Poral vestibule always much deeper than the 

 oscular cloaca. Colour pale buff, the interior being lighter. 

 Surface level but rough, forming a firm cortex, apparently devoid 

 of pores. Beneath the semi-translucent surface a network of 

 white strands visible. 



Skeleton mainly formed of bundles of trisenes and oxea radiat- 

 ing from centre to periphery, and embracing the pora! and 

 oscular depressions ; skeletal cortex formed of the cladal ends of 

 the trisenes and of tangentially arranged oxea, the clear spaces 

 visible thrpugh the surface being partly filled in by the ends of 

 the radiating bundles. In the walls of the poral and oscular de- 

 pressions, slender tufts of trichodal prodisenes spreading out in 

 fan-like manner as they approach the surface- 



Spicules. Megascleres. — Oxea (Fig. la). 8 to 10 mm. X -oS to 

 -T mm., slightly curved, sharp-pointed. Tylotes 3100 X -' ^> 



* In a letter received by me after the proofs of this paper were printed, 

 Dr. Gilchrist writes:— "Very large specimens of this species [Crateromorpha 

 lankesteri) were got, the diameter of one of the largest being about three feet. 

 Attempts were made to preserve these, bnt when dried they crumbled on handling. 



