282 "ENDEAVOUE" SCIENTIFIC RESULTS. 



"borders" between perfectly rounded (circular or oval) "cell- 

 apertures:" the effect is analogous to that which would be 

 produced in a species (like E. rotunda) with large "cells" 

 separated by vertical lamellae, if the outer edge of the lamellae 

 were to expand into a broad horizontal flange, thus concealing 

 the lamella? themsehes and reducing the size of the "cell- 

 apertures. " 



Of the half-dozen specimens in the Australian Museum, the 

 largest (shown in PI. xxix., fig. 2) is that which Whitelegge 

 {loc. cit.) mistakenly supposed to be the type of Plectispa 

 elegans ; it measures 230 mm. in height, and is thus not so 

 tall as the largest of Lendenfeld's specimens, which measured 

 300 mm. In the dry state, the sponge varies in colour from 

 brownish-grey to dark brown, and is of compressible and 

 elastic consistency ; there is some peculiarity in the texture of 

 the sponge which produces a "soft" appearance, suggesting 

 that of felt. Whitelegge's statement that the sponge is 

 "rather brittle when dry," is true only of his "type" specimen, 

 mentioned above ; the brittleness in this case appears to be due 

 to decay. Both Lendenfeld and Whitelegge have stated that 

 the echinating styli are shorter than those which core the 

 fibres ; I fail,, however, to find any difference between them. 

 Also I find that the auxiliary megascleres are invariably 

 strongyla — not subtylostyli, as stated by Whitelegge. 



I.ocs. — The species is known only from two closely situated 

 localities, Port Jackson and Tuggerah Beach. 



ECHIXOCI.ATHRIA ROTUXDA, Sp. nov. 



(Plate XXX., fig. I, and fig. 64.) 



Sponge oval or pear-shaped, unbranched, symmetrical. 

 The lamellce throughout are arranged parallel}' to the 

 lines of growth of the sponge, and at the surface, accord- 

 ingly, are disposed edgewise to the exterior; in the inner 

 region of the sponge they are elongated and so form the 

 partition-ivalls of radially disposed tubes. External ''cell- 

 apertures" hexagonal or (occasionally) elongate, on the 

 average about 4 mm. in width. Skeleton consisting of 

 subparallel mulli- or pauci-spicular main fibres joined by 

 interreticulating iini- and a-spicular connecting fibres. 

 Echinating styli plentiful, confined to the outer aspect of 

 the fibres. Scattered auxiliary spicules fairly abundant; 

 interstitial principal styli scarce. Megascleres : — {i.) 

 Principal styli, straight, rvith slight sub-basal waist ivhen 

 fully grown, *ubfusiform in younger stages, size 80 to 125 

 .V J. 5 |i; («.) auxiliary amphistrongyla, or occasionally 

 subtylo strongyla, size 120 to lyo x 2 p,. Microscleres :— 

 Slender isochelce palmatce, moderately abundant, 9 to 

 12 p, long. 



