﻿SPONGES.-HALLMANN. 



191 



spongin. The principal and auxiliary styli are usually 

 characterised by a barely appreciable sub-basal constriction. 

 The auxiliary styli are occasionally, the special dermal styli 

 frequently, provided with a minute basal spination. The 

 acanthostyles are stout, with relatively few large spines, and 

 without basal enlargement. The maximum dimensions of the 

 spicules are as follows : — 



Megascleres. — 



(i.) Principal st\li, 200-230 



(rarely 240) x 11-13 l^- 

 (ii.) Acanthostyles, (50-75 ^ 



7-8 ji. 

 (iii.) Auxiliary styli, 260-280 



X 7-9 /(. 

 (iv. ) Special dermal st\li, 



usually less than 130 (or 



perhaps 120) x 4.5 ji. 



Mic roscle res . — 



(i.) Larger chela?, (apparently) 



rather rare, 15-19 ii long, 

 (ii.) Smaller, usually contort, 



chelce, 7-12 n long. 



(iii.) Toxa: observed lengths, prl'i^mus. a Basal extremi- 

 90-260 \i. tiesof principal styli. b Acan- 



thostyli. 

 This \ariet}- differs from the 

 typical form in regard to the acan- 

 thostyles, which, for the latter, have been described as 

 "clavate. " 



Loc. — Henlev Beach, St. Vincent's Gulf, South Australia 

 (Austr. Mus. Coll.). 



A', typiciis var. 



Rhaphidophlus tvpicus, var. gemimjs, var. nov. 



(Plate xx\iii., hg. 4, and Hg. 38.) 



In regard to external form, there is not much to dis- 

 tinguish this variety from the preceding. The single specimen, 

 which measures 220 mm. in height, is a luxuriantly branched 

 stipitate sponge with rarely anastomosing branches, which 

 divide dichotomously, and extend with more or less overlap- 

 ping approximately in one plane. A peculiar feature of the 

 sponge, and one which will probably prove to be characteristic 

 is the unevenness of the surface of the branches, due to con- 

 ca\e depressions and short obliquely longitudinal undulations. 

 As a consequence the cross-section of a branch varies from 



