Mr. IT. J. Carter on the Genus Rossella. 121 



their maximum size, length, and density — average length 3.| 

 inches : 3. crucially headed, like no. 3 in R. atiiarcttca and 

 similarly situated (that is, issuing from the summits of the 

 monticular or boss-like eminences), but larger and more nu- 

 merous, averaging in tlie length of the shaft 7-12ths, and in 

 that of the arms 6-12ths of an inch respectively. B. Struc- 

 tural spicules of the body and latticework layer, the same as 

 in li. antarctica. C. Flesh-spicules, the same as those in R. 

 philippensis. Size of entire specimen 2,\ by 2 inches in its 

 greatest diameters ; aperture 8-12ths of an inch wide ; cavity 

 1 \ inch deep. 

 Hah. ^larine. 



Loc. Atlantic Ocean-bed, north-west of the Shetland Islands. 

 Ohs. The specimen of R. velata from which the above 

 description has been taken is that figured by Prof. Thomson 

 in his ' Depths of the Sea' (p. 418). It came to me dry and 

 not labelled ; but in a jar numbered " 65," received also at 

 the same time, there are, among other sponges, three fragments 

 of R. velata, which, according to the position of the station 

 which is indicated by this no. (viz. about 80 miles north-west 

 of the Shetland Islands), must have been dredged up in 345 

 fathoms. Nothing, however, can give a better idea of the 

 sponge, except seeing it, than the representation to which I 

 have alluded ; and therefore it will not be here repeated. 



R. velata differs from R. antarctica in the absence of the 

 erect fringe of spicules round the aperture, and, of course, in 

 not possessing that form of rosette or fiesh-spicule which is 

 peculiar to the latter. It differs from R. 2)hili2)j)ensis in pos- 

 sessing the covering of veil-spicules, whose crucially anned 

 heads form by intercrossing with each other an external en- 

 velope common to both R. antarctica and R. velata, as well 

 as in the absence of the peculiar form of rosette in R. 

 antarctica. 



From R. philippensis it also diffei's in possessing the stelli- 

 form boss-like surface, and in the absence of the mammiform 

 prolongations of the body with the large hair-like locks of 

 anchoring-spicules that issue from them respectively, Avhich 

 are equally absent in R. antarctica (PI. X. figs. 1 & 4) ; 

 lastly, in having for the most part the outer and inner arm 

 of the sexi-adiate spicule of the latticework dermal layer 

 developed as in R. antarctica, together with a profusion of 

 veil-like spicules, with probably other minor dificrences, which 

 being merely in degi-ee do not merit further mention here, 

 although generally they indicate, from their delicate nature 

 when compared with the other species, the quiet habitat in 

 which R. velata has been developed. 



