﻿SPONGES.- HALLMANK. 



249, 



more or less towards its extremity. Quite com- 

 monly the basal extremity of the spicule is either 

 abruptly or acuminately pointed, and the spicule ac- 

 , cordingly sometimes passes into an asymmetrical 



oxea. The length varies from 140 to ijofi and the 

 maximum diameter is 4 f/. 



(ii.) The (accessory) acanthostyles are sub-conical, with 

 moderately large, irregularly scattered, recurved 

 spines. They are rarely less than 60 fi long and 

 attain a size of 96 x 8 ^. 



Microscleres. — 



The chelce (isochela? arcuatae) vary from about 18 to 27 \i in 

 length ; except for a greater curvature of the shaft in the case- 

 of the shorter spicules there is no appreciable difference in 

 form between the longest and the shortest. In their earliest 

 stage of development they appear as a slender, slightly curved 

 rod ; the alae are well advanced in development before the 

 rudiment of the front palm makes its appearance. At a certain 

 stage of their growth many bear a rather close resemblance to- 

 the longest of the three chela? shown in text-figure 52a for 

 WilsGneUa oxyphila. 



Loc. — Coast of South Australia; (?) fifteen miles south of 

 St. Francis Island ("Endeavour.") 



WiLSONELLA OXVPHILA, Sp. ilOV. 



(Plate xxxiv., fig. 3; and figs. 52, 52a.) 



Sponge flahellate, simple or proliferous. (?) Oscula- 

 small, marginal. Surface even, or with faint radiating 

 grooves, or areolately pitted. Dennal membrane dis- 

 tinct, thin. Main skeleton an irregular reticulation of 

 moderately slender, closely echinated fibres, with a 

 slender core of skeletal spicules. Interstitial spicules 

 scarce. Megascleres of both kinds {the accessory in 

 lesser number) are sparsely scattered in the dermal mem- 

 brane, together with frequent chelce. Megascleres :- — 

 (/.) Skeletal smooth substyli, 200 x j y,; {ii.) accessory 

 acanthostyli and {occasional) acanthoxea, 80 x 4.5 ji. 

 Microscleres : — Isochelce arcuatcs, approaching the 

 palmate form, 16 to 26 ji long. 



Introductory Remarks. — There are two specimens which I 

 assign to this species. In their external appearance there is 

 nothing that would suggest a specific identity, but they agree 

 so perfectly in their spicular characters that one hesitates to 

 separate them even as different \arieties. Accordingly I have 

 thought it best, whilst uniting them under a single name, to. 



