﻿;^48 



"ENDEAVOUE" SCIENTIFIC RESULTS. 



only, with a thin core of skeletal styli. Interstitial 

 spicules rare. Megascleres of both kinds {the acantho- 

 styles in lesser numher) occur sparsely in the dermal 

 membrane, together with scattered chelce. Megascleres : 

 — (i.) Skeletal, smooth substyli, i6o x 4 p; (//.) accessory 

 acanthostyli, g6 x 8 p. Microscleres : — Isochelce arcuatce 

 18 to 2^ p long. 



The single specimen, preserved in alcohol, consists of a 

 sub-cylindrical stalk (about 80 mm. long by 15 mm. in dia- 

 meter) from which by two dichotomies there arise four erect 

 slightly compressed branches. The branches are closely 

 appressed and coalescent. Distantly separated oscula, seldom 

 more than 1 mm. in diameter, occur in an irregular series 

 along the edges of the branches. The surface is free from 

 inequalities. 1 There is a very thin but quite distinct dermal 

 membrane. The texture is dense ; the 

 consistency, firm and fairly tough ; the 

 colour, yellowish-brown. The total 

 height of the specimen is 325 mm. 



The main skeleton is an irregular, 

 relatively small-meshed reticulation of 

 rather stout spongin fibres (sometimes 

 exceeding 200 y in diameter) somewhat 

 densely echinated by short acantho- 

 styles. In general, the area occupied 

 by the fibres themselves is greater than 

 that of the intervening spaces. A small 

 proportion of the fibres are provided 

 with a slender compact spicular core, 

 but except in this respect there is no 

 evident distinction between main and 

 connecting fibres. A notable feature of 

 the skeleton is the almost entire ab- 

 sence, except in close vicinity to the 

 surface, of interstitial scattered megas- 

 cleres. The dermal membrane contains 

 scattered megascleres of both kinds (the 



acanthostyles in lesser number) and fairly numerous chelte ; 



the last-mentioned, also, are somewhat scarce in the choano- 



somal tissues. 



Megascleres. — 



(i.) The (auxiliary) smooth spicules are sharp-pointed 

 cylindrical subtylostyli (or less frequently simple 

 styli) with an elongate tylosis which usually tapers 



Fig. 51— IV. curvi- 

 chela. a Showing 

 basal ends of the 

 styli a Distal ex- 

 tremity of same, b 

 Acan thostyle. c 

 Chela. 



1 The transverse ridges shown in the figure were produced by an en- 

 twining sea-weed. 



