Mr. H. J. Carter on the Genus Rossella. 121 
their maximum size, length, and density—average length 37 
inches: 3. crucially headed, like no. 3 in &. antarctica and 
similarly situated (that is, issuing from the summits of the 
monticular or boss-like eminences), but larger and more nu- 
merous, averaging in the 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 R. antarctica. c. Flesh-spicules, the same as those in 2. 
philippensis. Size of entire specimen 2,8, by 2 inches in its 
greatest diameters ; aperture 8-12ths of an inch wide; cavity 
13 inch deep. 
Hab. Marine. 
Loc. Atlantic Ocean-bed, north-west of the Shetland Islands. 
Obs. The specimen of &. 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. 
. velata differs from &. antarctica in the absence of the 
erect fringe of spicules round the aperture, and, of course, in 
not possessing that form of rosette or flesh-spicule which is 
peculiar to the latter. It differs from A. philippensis in pos- 
sessing the covering of veil-spicules, whose crucially armed 
heads form by intercrossing with each other an external en- 
velope common to both &. antarctica and L. velata, as well 
as im the absence of the peculiar form of rosette in R. 
antarctica. 
From R&. philippensis it also differs 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, which 
are equally absent in &. antarctica (Pl. X. figs. 1 & 4); 
lastly, im having for the most part the outer and inner arm 
of the sexradiate spicule of the latticework dermal layer 
developed as in &. antarctica, together with a profusion of 
veil-like spicules, with probably other minor differences, which 
being merely in degree 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. 
