HEXACTINELLIDS WITH DISCOCTASTERS. 



51 



ing a continuous lattice-work with quadrate meshes. The free proximal 

 rays do not differ in character from the rest. 



Locality : Sagami Sea. I have myself collected some specimens 

 from depths of 274 fathoms and upward. 



3. Rhabdocalyptus capillatus, n. sp. 



Sac-like or vase-like, more or less strongly compressed. Oscular 

 edge fringed with thin needle-like prostals, not outwardly expanded. 

 Dermal surface thickly beset with pentactin prostalia which stand out in 

 tufts from every hypodermal centre and form a thick tolerably firm 

 gossamer-like layer all over the surface. The body may attain a height 

 of 210 mm. 



Parenchymalia may contain bow-like diactins of 24 mm. in length. 

 Discoctasters are very small, measuring only 38-55/v. in radius, and are 

 of very characteristic shape. From a principal there arise 6-12 slender 

 terminals, which are always bent in an S-like manner and form a bunch 

 considerably expanded at the extremity. Terminal discs pin-head like. 

 Discoctasters are most numerously found in the gastral layer. 



Oxyhexasters and microdiscohexasters as in Rh. mollis, but the 

 former have no or but little developed basal barbs. Hexactin-shaped 

 oxyhexasters are rare. 



Autodermalia likewise as in foregoing spacies. Hypodermalia con- 

 sist solely of paratropal pentactins, which are grouped in closely con- 

 centrated centres. The older and pronged ones destined to be protruded 

 as pleural prostalia, have paratangential rays that may reach 12 mm. in 

 length and a still longer shaft. 



' Autogastralia, forming a continuous quadrate mesh-work, consist of 

 rough hexactins with pointed ends, the free proximal ray being longer and 

 supplied with better developed microspines than all the rest of their rays. 



Notwithstanding the close similarity of spicules, this species is easily 

 distinguishable from Rh. mollis by the smaller size and characteristic 

 shape of discoctasters, by the larger size and the persistence of pentac- 

 tin prostalia, etc. 



