24 Mr. H. J. Carter on the Gumminese. 



stellate 5-6000ths. Size of largest specimen about 3 inches 

 long, 1 inch broad, and £ inch thick, covering a tunicated 

 ascidian ; the other specimen about 2| long by 2^ broad, 

 and the same thickness, enclosing the valves of an oyster. 



Hab. Marine, growing over various objects and upon other 

 sponges. Incrusting for the most part, but sometimes self- 

 supporting, in the form of caudal or mammilliform prolonga- 

 tions. 



Loc. Australia, Port Jackson. 



Obs. The sphsero-stellate spicule (fig. 16, a) being identical 

 in form with that of Ghondrilla nucula, Sdt., I have called this 

 species " G. australiensis" In consistence, C. nucula (judging 

 from Schmidt's specimens in the British Museum) appears to 

 have been a little firmer, of a darker colour on the surface, and 

 far more spiculiferous ; but then it only possesses one, the 

 sphaero-stellate form of spicule, while the Australian species has 

 two. In other respects there is a great resemblance between 

 thf two species, although, probably from defective preservation, 

 the characteristic epithelial layer of the excretory canals of the 

 Gumminese generally has here, for the most part, passed into 

 dissolution. 



There are two specimens in the British Museum, both from 

 Port J ackson — one, as above stated, surrounding the deciduous 

 valves of an oyster, and the other all but covering a large tuni- 

 cated ascidian fixed to the detrital mass supporting a rough, mu- 

 ricated, brown specimen of Hircinia, which contrasts strongly in 

 appearance with the smooth, doughy, fleshy-looking Gummina. 



The ovoid cells in this species are fully double the size of 

 those in Gorticium abyssi, and filled or lined, as above stated, 

 with minute cellulae, whereby we may infer that the so-called 

 granules filling the ovoid cells of Gorticium abyssi (fig. 14, b) 

 would also turn out to be cellules, if more highly magnified. 

 There is no visible cell-wall on these cells; but its existence may 

 be inferred from the group of cellules retaining the same ovoid 

 form after they have been pressed out of the cavities in the 

 trama, unless they cohere together in this form by their sar- 

 code individually. 



General Observations. 



The group of sponges called by Schmidt " Halisarcinae Gum- 

 minege" (Atlantisch. Spongienfaun. p. 78), to which the two fore- 

 going species belong, has been very little studied — partly, per- 

 haps on account of the species having been overlooked among 

 the Compound Tunicata, which are much in the same condition, 

 and partly because they are so totally unlike the form and 

 appearance of sponges generally. 



