SPO-\GES.-HALLMANX. j -^^ 



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, 

 perceiving that although such a step may prove 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, Carter, var. ferramosa, var. uov. 



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



Spn}2ge ramose, erect, stipitaie : witli long and rela- 

 tively slender cylindrical branches ivhich multiply dichot- 

 onwjisly and occasionally anastomose. Osada? The 

 )nain skeleto)i is reticulate, though connecting fibres are 

 relatively feu' i)i niindwr. The fibres are not densely 

 cchinated and coiitain a stout compact core of oxea 

 nnngled it^uth a moderate number of acantho styles. 

 Dermal skeleton? Megascleres, maximum sizes: — (i.) 

 Oxea, 195 .V 'j-.^ II : (ii.) principal acanthostyles, 160 x 

 72 fi; (ill.) dermal acanthostyles about 100? x 7 j.i. Jso- 

 chelce arcuatce, ij to 25 ^ long; imperfectly distinguish- 

 able into tivo ki)ids, a larger and a smaller. 



This variety is represented by a single specimen 520 mm. in 

 height (Plate xxiv.). 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 owing 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 even when most abundantly de- 

 veloped these spicules stand, on an average, probably not less 

 than 20 ji apart. 



Megascleres.— 



{'i.) The oxea varv in length from 160 to igo;/ ; the stoutest 

 occasionally reach a diameter of 7 ji. A greater pro- 

 portion of them than in an>' of the other varieties 



