506 Mr. H. J. Carter on 



icall of tlie tube, tlius leaving the surface towards the " inter- 

 vals " smooth, by which the "tube" and the "interval," by 

 contrast, are sharply differentiated ; tubes or tubulation, as 

 before stated, in direct communication with the cloaca through 

 its infundibular depressions, becoming more or less tortuous, 

 branched, and anastomosing as they extend outwards towards 

 the surface, where they become divided and sigmoidally plicated, 

 ending in the quasi fibro-reticulate ridges, whose structure is 

 pierced by the pores, as above noticed. " Intervals " smooth, 

 more or less in communication with each other, so as to appa- 

 rently form a general chamber, which is shut off from the 

 cavity of the cloaca, except through the "subsidiary apertures " 

 just mentioned, opening on the surface through the " small and 

 large vents " already described. " Subsidiary apertures " 

 in the cloaca on a level with its surface, not in the infundi- 

 bular depressions, not echinated, but marginated by a thin 

 rim of sarcode, irregular in shape, size, and position. Wall 

 of the " tubes " plentifully pierced by pores between the 

 arms of the radiates, and the same with the lining structure or 

 membrane of the cloaca ; in short, there seems to be no sur- 

 face in which theT/ are absent, on all occasions. Spicules of 

 two kinds, viz. triradiate and quadriradiate. Triradiate of two 

 forms, viz. : — 1, large, equiarmed and equiangulated, with the 

 arras bent downwards and outwards sigmoidally, all together, 

 like a "three-leggedstool," each arm about 29 by 6-6000thsin., 

 and the summit of the tripod about 24-6000ths in. from the 

 base ; 2, simple, triradiate, equiarmed, equiangulated, arm 

 about 25 by 2^-6000ths in. in the average largest size ; ,'{, 

 quadriradiate, about the snme size as the foregoing, with the 

 addition of the fourth ray, which for the most part is long, 

 curved, and varies in length under 30-6000ths in. The tri- 

 podal form of the triradiate is confined to the ridges on the 

 surface, where it is rather sparse ; the common form to the 

 surface generally, and the quadriradiates to the tubulation and 

 surface of the cloaca respectively. Size of the largest speci- 

 men possessing a mouth (for there are three or more in the 

 collection) 2^ in. high by a maximum of ]|x 1 in. horizon- 

 tally ; cloaca | by | in. horizontally ; mouth f by f in., also 

 horizontally. Auloplegma-form like a goose-egg, 3 in. in its 

 longest diameter by a maximum of 2| x If in. horizontally; 

 cloaca 2i in. in its longest diameter, by l:f x | in. horizontally ; 

 wall about | in. thick. 



Ohs. The most striking part of this species is the tubular 

 ecMnation, with regard to which it may be observed that, if the 

 current is to be indicated by the direction of the curve of the 

 fourth ray of the quadriradiates, as in the cloaca of Grantia 



