﻿SPO-\GES.-H ALL.\1 A N .\. I -f. 



is nothing in what has been written concerning the latter ex- 

 cept the reference to its habit of growing over Pecten shells, 

 which furnishes any warrant for regarding the two as identical. 

 Accordingly, after some hesitation, I have decided to introduce 

 a distinguishing varietal name for the Oyster Bay sponges, 

 percei\ing that although such a step ma}- pro\e to be incor- 

 rect, it cannot at any rate give rise to confusion. 



Loc. — Oyster Bay, Tasmania, 30 fms. ("Endeavour.") 



Crei.la IN'CKUSTA.NS, ('drier, YAK. PKRRAMOSA, vur. nov. 



(Plate xxi\. , and hg. 30.) 



Sponge ramose, erect, siipitaie ; lanth long and rela- 

 tively slender cylindrical branches which multiply dichot- 

 onioiisly and occasionally anastomose. Oscitla? The 

 main skeleton is reticulate, though connecting fibres are 

 relatively few in number. The fibres are not densely 

 echinated a)id contain a stout compact core of oxea 

 mingled witli a moderate number of acantho styles. 

 Dermal skeleton? Megascleres, maximum sices: — (f.) 

 Oxea, J95 A y.^ n; (ii.) principal acantJiostyles, 160 x 

 12 ]i; {Hi.) dermal acanthostyles about 100? x 7 }i. Iso- 

 chelce arcuatce, ij to 2^ ]i long ; imperfectly distinguish- 

 able into two kinds, a larger and a smaller. 



I his \ariety is represented by a single specimen 520 mm. in 

 height (Plate xxiw). The branches are cylindrical, except 

 in places where they broaden out prior to bifurcation. The 

 specimen is preserved in a dry state, and so affords no informa- 

 tion concerning the oscula or the arrangement of the dermal 

 skeleton. The main skeleton bears a considerable resemblance 

 to that of the variety digitata, but differs o\\ ing to the rather 

 frequent occurrence of transverse connecting fibres. The 

 main fibres are sinuous, and interosculate to form a loose 

 pseudo-reticulation. They contain a compact core of spicules 

 20 to 80 fi in stoutness which as a rule is almost entirely 

 formed of oxea; occasionally, however, acanthostyles — both 

 principal and accessory — become the predominating elements 

 of the core. Echinating acanthostyles are only of moderate 

 abundance ; the fibres are sometimes lacking in them for quite 

 considerable distances, and e\ en when most abundantly de- 

 veloped these spicules stand, on an average, probabl}- not less 

 than 20 }i apart. 



Megascleres. — 



(i.) The oxea vary in length from 160 to i<)0 j( ; the stoutest 

 occasionally reach a diameter of j fi. A greater pro- 

 portion of them than in any of the other \arieties 



