508 Mr. H. J. Carter on 



or tubulation, arouud the cloacal cavities just mentioned, 

 which respectively descend, narrowing towards the base and 

 widening upwards until they become contracted again towards 

 the vent. Tube composed of a single layer of triradiate spi- 

 cules onli/, held together by the sarcode and its accompanying 

 soft parts, among which, in this instance, a number of ova are 

 present, which, by their size and the presence of the germinal 

 vesicle, indicate that they are near to segmentation ; traversed 

 plentifully by pores, and opening here and there by circular 

 holes into the cloacal dilatations, which is probably the case 

 throughout the interstices of the reticulation generally ; both 

 the tubulation and the interstices varying greatly in diameter 

 under 1-lOOth. in., largest on the surface of the cloaciform 

 dilatation, smallest towards the circumference. Spicules of 

 one kind only^ viz. triradiate, but of tioo distinct forms, 

 as in the foregoing, viz. : — 1, tripod-like, stout, with the 

 arms bent downwards and outwards sigmoidally, about 20- 

 GOOOths in. high^ spreading to about 20-6000ths at the base, 

 arms about 21 by 6-60OOths in their greatest dimensions 

 respectively ; 2, the common form of triradiate, but much 

 thinner than the foregoing, with arms more or less equal 

 and more or less equiangled, varying in measurement under 

 20 by l-6000th in. The former very abundant and almost 

 entirely confined to the ridges formed by the reticulated tubu- 

 lation on the surface, the latter to the interior. No quadri- 

 radiates. Size of specimen, which is compressed and nearly 

 equilateral, y\ ^^' liigli> upper border ^ in. long, thickness of 

 body ^ in. 



Ohs. There can be no doubt that this is the same sponge as, 

 only in a larger form than, that which I described and illus- 

 trated under the name of ^^ Leucetta clathrata'^ ('Annals,' 

 1883, vol. xi. p. 33, pi. i. tigs. 13-17) ; but we have here the 

 tubular thread in a larger and distinctly hollow state, and not 

 solid as assumed to have been the case in Leucetta clathrata^ 

 where, from contraction during desiccation, it had become 

 solid, which, together with the smallness of the specimen, 

 misled me into stating that it was " not hollow " {op. cit. 

 p. 34), a mistake that I am thus able to have the opportunity 

 of correcting, and of changing at the same time the name to 

 Clathrina tripodifera^ var, gravida, on account of the presence 

 of the ova, above mentioned, which are in much the same 

 condition as those in Clathrina tripodifera, whose descrip- 

 tion and dimensions have just been given. Hence the neces- 

 sity of extended experience in laying down specifically the 

 typical form of a sponge. 



Of course, here we have the same structure as in Clathrina 



