W. LEUCKARTI. — SPICÜLATION. 291 



The delicate ony chaster (PI. XIII, figs. 15-17) is of inucli 

 the same appearance as in W. flemmingi. It is rather rare, at 

 any rate not common in all parts. While in most preparations 

 it required a prolonged search to discover one, in others several 

 were found side by side among the parench3^mal diactins. This 

 gave me the impression that the onychasters were in the main 

 more deeply situated than the spherical discohexasters, though 

 sometimes both occurred in intermixture. 



Diameter 68-84 ji. The principals are very short, thick and 

 swollen at the ends ; each bearing 3-6 (rarely more), exceedingly 

 fine and strongly divergent terminals. These arise from the 

 principals without regularity in arrangement, not in a whorl 

 (fig. 16). They generally taper towards the outer end, which is 

 capped by a whorl of gently recurved, minute claws, usually 4 

 or 5 in number. The cap, though somewhat more strongly 

 developed in some cases than in others, is ordinarily so small 

 as to require careful observation under a high power in order 

 not to overlook it. In several instances the terminals revealed 

 no claws even when examined under the immersion system, but 

 seemed actually to end with a minute pinhead-like knob. 

 Moreover, the excessively fine outer ends of the terminals easily 

 break off; so that the chances of the hexaster in question being 

 erroneously taken for an oxyhexaster are great. Moore seems 

 to have fallen into this error. 



The graphÂocome (PL XIII, fig. 11) is of typical form. It 

 is very large, reaching almost 450 /^ in diameter. Sheaf of 

 rhaphidial terminals 200/^ long and 20// broad; the central, 

 hexradiate principals 26 /^ in axial length. As usual the graphio- 

 comes are confined to the periphery of the sponge. In the perfect 



