REPORT ON THE HEXACTINELLIDA. 93 



the projecting distal of the hypodermalia. All the hypogastralia are somewhat uniformly 

 rough. It has not been determined with certainty whether the numerous floricomes which 

 are represented on PI. XVIII. figs. 6, 7, 9, and which appear abundantly on certain 

 portions of the inner surface, really adhere to the projecting proximals of the hypogastralia. 

 These inner floricomes difler from the outer, moreover, not only in their smaller size, but 

 also in the fact that the slightly bent terminals, which occur to the number of six or more 

 on every principal ray, bear small barbs in addition to the many pronged terminal plate 

 (PI. XVIII. figs. 6, 7). 



2. Malacosaccus unguiculatus, n. sp. (PL XIX.). 



To the south of Sierra Leone (Station 348, lat. 3° 10' N., long. 14° 51' W.) there was 

 collected from a depth of 2450 fathoms, and on grey mud, a saccular sponge, 3 cm. in 

 length and 1"5 cm. in breadth, with walls measuring from 1 to 2 mm. in thickness. The 

 inferior extremity was torn ofi", and the superior margin only preserved in an injured 

 condition. The outer surface is slightly rough, but on the whole uniformly even, while 

 the inner surface, on the other hand, is perforated by numerous canalicular orifices of 

 varied breadth (PI. XIX. fig. 1). 



The principalia of the parenchymal skeleton are represented by slender hexacts with 

 long, narrow-, smooth and flexible rays, which are disposed radially, longitudinally and 

 transversely, and apply themselves by corresponding rays to one another, or to the 

 prolonged parenchymals of the hypodermalia and hypogastralia, so as to form a loose 

 network which permits of the bending and folding of the whole sponge-wall. The 

 parenchyma also includes numerous oxyhexasters with slender, straight, or slightly bent 

 terminal rays, of which three occur in most cases on each of the comparatively short 

 principals (PI. XIX. fig. 7). Delicate discohexasters also occur, with thin terminal rays 

 which are somewhat thickened outwardly, and which bear upon their outer extremities 

 a whorl of four or more backwardly bent, thin, transverse spines (PL XIX. fig. 3). 



The hexact hypodermalia have a thickened distal ray beset with scaly teeth, and a 

 greatly prolonged proximal, which, like the moderately long transverse rays, is seldom 

 quite smooth, but is, as a rule, more or less richly beset with small pronged elevations 

 (PL XIX. figs. 2, 4). 



The hypogastralia are very similar to, but are distinctly more slender than the 

 hypodermalia (PL XIX. fig. 2). 



Floricomes are not found on the outer surface but appear here and there on the inner. 

 They bear three or four terminals on every principal ray. The thickened outer extremity 

 of every terminal ray runs out into an overhanging plate with two or three strong 

 terminal claws (PL XIX. figs. 5, 6). 



Although I did not find these floricomes upon the inwardly projecting proximal ray of 



