4 ^Ir. H. J. Carter on tlie Suhspherous Sponges. 



Size variable, tliat of specimen figured 3 inches in its longest 

 diameter. Colour : — corticular portion grey, body bright 

 orange, nucleus pink. 



Hah. South-east coast of Arabia, opposite the north-east 

 end of the island of Masira. Free or fixed to the rocks along 

 the shore. 



Ohs. I found several specimens of this sponge about the 

 locality mentioned ; some were floating or rolling about in the 

 land-wash, and others fixed to the rocks — the latter with, and 

 the former of course without, point of attachment. It is pro- 

 bable that those portions alone float which, having got out of 

 the water for a little time, get some air in them, and that 

 when this is extricated they again sink to the bottom. The 

 sarcodal substance of this s^Jonge is so rigid and contrac- 

 tile that, when alive, it can with difficulty be torn to pieces. 

 Those on the rocks appeared to me to get more rigid in pro- 

 portion as I tried to get them oflf, until at last I was obliged 

 to apply my geological hammer and chisel to them. The 

 forcible power of contractility here, as well as in Tethya Jyn- 

 euriumj which I shall presently describe, may partly account 

 for the compact character of the sponge-substance after death, 

 and the comparative absence of the excretory system of canals 

 probably arising therefrom, in both these species. T. arabica 

 very much resembles T. cranium of our own shores ; but I 

 found no gemmules in it, like those figured and described by 

 Johnston and Bowerbank respectively as peculiar to the latter 

 species ; nor does the surface of the Arabian species agree with 

 that of T. cranium figured in Johnston's ^British Sponges.' 

 It appears nevertheless to be the representative of the latter on 

 the south-east coast of Arabia. 



In one small portion of the surface which I examined there 

 happened to be several stoutish triradiate spicules, with their 

 rays expanded in the corticular part, like those of Oeodia — 

 showing, by this occasional occurrence, how such characters 

 may be present in species otherwise distinctly different. 



On treatment with iodine, faint traces of starch made their 

 appearance in the globular contents of certain little cells, but 

 not of the gemmules, which turned amber-colour. 



When dry, the surface of this sponge presents a glistening 

 asbestiform appearance, from the number of delicate spicules 

 which project beyond the dermal sarcode, 



Oeodia {Cydonium, Gray) arabica^ mihi. PI. I. figs. 9-16. 



Globular, free or fixed. Surface hard, hispid, covered with 

 a short hirsute dermal sarcode (where the latter is not abraded) 

 densely charged with minute smooth spicules, beneatli A\hich 



