DENDY— HOMOSCLEROPHORA AND ASTROTETRAXONIDA -257 



16. Erylus lendenfeldi SoUas. 

 (Plate 47, fig. 4.) 



Stelletta euastrum Carter [1880 b, p. 136], not Schmidt. 

 Erylus lendenfeldi SoUas [1888]. 



I am not aware that this species has been met with since it was first described by 

 Carter in 1880 fi^om Fremantle, Western Australia, and Carter's description was taken 

 from a single dry specimen. It seems therefore worth while to describe it again. 



The single specimen in the "Sealark" collection is cushion-shaped, subspherical, 

 about 16 mm. in maximum diameter. It has been torn off from some attachment below. 

 It bears a single circular vent, about 2 mm. in diameter, not far from the centre of the 

 upper surface, without any oscular collar or fringe of any kind. The inhalant pores are 

 distinctly visible under a pocket lens, scattered irregularly and singly over the general 

 surface, each with a narrow whitish margin ; sometimes widely open and sometimes closed 

 to varying extents. The surface is smooth and of a dark, greyish-brown colour ; the 

 interior is yellow. Texture firm and fairly compact, but with a wide oscular tube 

 running up to the vent and appearing (broken across) on the lower surface, which 

 suggests that there may have been a good deal more of the sponge below. 



Skeleton confused internally, radially arranged towards the surface, consisting 

 principally of large oxea but with a fair number of orthotritenes typically orientated 

 beneath the cortex of aspidasters. 



Spicules : — (l) Orthotrisenes (Plate 47, fig. 4 a) ; with well-developed cladi, typically 

 unbranched but sometimes irregularly bent and even forked ; shaft and cladi tapering to 

 more or less sharp points (often blunted). Size variable, a typical specimen gave the 

 following measurements : — shaft 0'5 by 0'034 mm. ; cladi 0'24 by 0'034 mm. 



(2) Oxea (fig. 4 h) ; slightly curved, tapering at each end to a sharp or blunt point, 

 measuring about I'O by 0"026 mm. 



(3) Aspidasters (figs. 4 c — 4 c"") ; much flattened, oval or irregular in outline, 

 surfaces beset with numerous small, scattered, simple or slightly stellate tubercles ; 

 dimensions about 0"17 by 0"082 mm. Young forms radially striate, formed by fusion 

 of slender rays proceeding from a central mass ; intermediates smooth, without tubercles. 



(4) Large oxyasters (fig. 4 d) ; with no distinct centrum and long slender rays, 

 minutely spined and not quite sharply pointed ; rays usually 4 in number, measuring 

 each up to about 0"07 by 0'004 mm. 



(5) Small oxyasters (fig. 4 e) ; similar to the last but with rays only about O'Ol mm. 

 long ; perhaps young forms ; abundant. 



(6) Polyactinose oxyasters (fig. 4/) ; with minutely spined, slender rays and no 

 distinct centrum. Total diameter up to about 0'028 mm. 



Intermediate forms between (4), (5) and (6) occur ; and some of the small asters may 

 have slightly tylote rays. 



(7) Microrhabds (fig. ig); smooth, curved, often centrotylote and usually bluntly 

 pointed at each end ; measuring, say, about 0"07 by 0"006 mm., but variable. 



SECOND SERIES— ZOOLOGY, VOL. XVII. 33 



