Sponges from South Australia. 449 



late 12-GOOOtlis in., head 2-60a0th3 in. longitudinally and 

 3-6000ths in. transversely, shaft 2-6000tlis in. thick in the 

 centre. Skeletal spicules alone forming the middle layer of 

 the large or lower main portion of the tubulation and that of 

 the branches throughout, as above described ; flesh-spicules 

 chiefly in the dermal layer, rather scanty. I see one simple 

 bihamate, about 8-6030ths in. long, in the mounted prepara- 

 tionj but cannot say for certain that it belongs to the spicu- 

 lation. Size of specimen 3 in. in length. 



Loc. Port Western. Depth not mentioned. 



Obs. 'J'his, as the above description will show, is a remark- 

 able sponge both in ]-espect of general form and spiculation, 

 irrespective of the peculiar mode of circulation. The struc- 

 ture of the wall of the poriferous portions is analogous to 

 that of the tubular appendage of a Phloeodictyon, viz. Desma- 

 cidon fistulosa &c. Whether the specimen has been simply 

 cut off from its base of attachment or from the body of a 

 large sponge I am unable to say ; but the difference in struc- 

 ture of the basal or larger portion and the quantity of fleshy 

 fibrous sarcode hanging out of it (fig. 1, d) would seem to 

 indicate that this was an extension of the body-substance of 

 the sponge, whatever the form of the rest might be. 



Halichondria scabida. Cart. 



Halichonclria scahida, 'Annals,' 1885, vol. xv. p. 112. 



In the collection from " Port Western " there are three 

 more specimens of this remarkable sponge, which I mention 

 more particularly to show how a number of specimens of the 

 same species may be necessary to describe the whole of the 

 adult forms that it may assume. 



Thus the first specimen described {I. c.) was " globular, 

 ■compressed, and sessile," whereas the largest of the specimens 

 from " Port Western" is branched and stipitate, 3^ in. high 

 by 3 X 2 in. horizontally ; the branches thick and flabeUi- 

 form, ending in subdigitate margins respectively; the largest 

 branch about 3 in. broad by \ in. thick. The next in size, 

 which has grown over the end of a large calcareous (?) Serpula- 

 tube, is pyriform in shape, and presents a nodose surface 

 whose nodes or humps are in high relief all over; while the 

 third is so small and shapeless that it is not worth description. 



All these forms may be easily derived from one another; 

 and this kind of transition is so common in the different species 

 of the Spongida, that it might be almost premised with cer- 

 tainty that at one time or another they may be found under 

 any one of them. Hence the futility of describing the adult 

 form of any species from a single specimen. 



