REPORT ON THE HEXACTINELLIDA. 117 



British Museum, I regard as identical with the sponge named Asconema setuhalense by 

 Saville Kent. The specimens in question were trawled at Station 4 of the "Triton" 

 expedition, from a depth of 327 to 430 fathoms, and were preserved in absolute alcohol. 

 By means of this fitly selected medium the soft parts were especially well preserved. 



The priucipalia of the parenchyma are strong, smooth diacts, 1 cm. or more in 

 length, pointed at both ends, and usually exhibiting in the middle a small knot-like 

 swelling. They lie laarallel to the bounding surface at diff"erent levels, and are distri- 

 buted with comparative irregularity. Every principal ray is surrounded by a layer of 

 thin diact comitalia which extend over its surface in gently undulating curvature. 



The parenchyma also contains a rich abundance of thin rod-like diacts of small size, 

 separately or in bundles, and disposed in different directions. Of these many exhibit a 

 central swelling (PI. XXI. figs. 7-10), and either terminate in sharp points (PI. XXI. 

 figs. 9, 10), or are provided with rough knob-like swellings on one or at both extremities 

 (PI. XXI. figs. 7, 8). 



Between all these rod-like spicules four different kinds of rosettes occur in ii-regular 

 distribution: — namely (1) simple oxyhexasters with long terminal rays, two or three in 

 number, and running out in a diverging manner from the principal (PL XXI. fig. 12); 

 (2) smaller oxyhexasters in which each of the broad, moderately short principal rays 

 bears a bundle of three to twelve fine terminals (PI. XXI. fig. G) ; (3) quite small disco- 

 hexasters in which each of the broad principals bears a strongly-developed, diverging 

 brush-like bundle of numerous fine terminal rays with terminal knobs (PI. XXI. fig. 3) ; 

 and (4) discohexasters twice the size of the above, with short principal rays, each of 

 which exhibits six long, thickly barbed, cylindrical terminals. These are disposed either 

 in a tuft or round a funnel-shaped space, and terminate in an arched terminal disc with 

 several prongs (PL XXI. fig. 11). 



The dermal skeleton is supported by tolerably large, simple, smooth hypodermal 

 pentacts. In the dermal membrane itself lie the four cruciate transverse rays of small 

 pentacts, from each of which a distal radial, as long as the transverse, projects outw^aixls, 

 while the proximal radial ray is reduced to a smaU rounded peg. The five developed 

 rays of these autodermalia are thickly beset with small outwardly directed prongs, while 

 the proximal stump appears to be smooth (PL XXI. fig. 4). 



The gastral skeleton is very similar. Here also large, smooth, pentact hypodermalia 

 (not introduced into the diagrammatic figure 2) are present. The gastral membrane 

 contains the cruciate transverse rays of pentacts, in which the proximal ray projects 

 inwards into the gastral cavity, while the radial is rudimentary. The five developed 

 rays, like those of the autodermalia, are beset wdth prongs. Between the pentact auto- 

 gastralia, hexacts also occur here and there. In these the distal ray enters into the 

 parenchyma, and has the same length and development as the proximal I'ay opposite to 

 it (PL XXI. figs. 2, 5). 



