| OCR Text |
Show 1881.] THE SURVEY OF H.M.S. 'ALERT.' 135 Examined. In spirit, and by sections in balsam and in spirit. Hab. Victoria Bank (off S.E. Brazil), 39 fathoms; bottom, coral. Six specimens, one young. Obs. This Sponge shows a considerable amount of variation in the size of the spicules in different specimens. One variety is especially well marked : its length is only twice as great as the breadth ; its acerates reach the diameter of -09 millim. and length of 3'6 millims., its triradiates increasing proportionally in size, the diameter reaching '05 millim. It appears to be most closely allied to A. {Leucandra) asperum, Hackel, from the Mediterranean, of described species; but differs from it in the inferior ratio of the thickness of the acerates to that of the triradiates, in the much thinner body-wall, in the larger and more slender apical ray of the quadriradiate, and in the formation of the oral fringe out of a special fine acerate form of spicule. APHROCERAS CAMINUS, Hackel (Plate XI. fig. 6), and var. CRASSIOR, sp. nov. (Plate XI. fig. 7). Leucandra caminus, Hackel, Kalkschwamme, ii. p. 175, pi. xxxi. figs, \a-\d, xxxvii. figs. 5 A, 5 B, 6. Three specimens occur in this collection from the same locality, two of which are apparently identical, and one differs considerably from them. The arrangement of the canal-system has not been made out very clearly; but it appears to be of the " traubenfiirmig" type described by Hackel {op. cit. vol. i. p. 233) in A. {L.) ananas, Montagu, &c. with small circular cavities scattered through the walls of the body. The two specimens, which agree with each other and with Hackel's description, are ovate, 6 to 7 millims. long by about 4 millims. broad; the body-wall is 1'5 millim. thick at the sides; the mouth is funnel-shaped owing to the downward convergence of the walls of a slightly projecting "collar," which is 2"5 millims. across; the body-cavity is about 1 millim. broad. The other specimen, which may be termed var. crassior, is 7 millims. long by 4 broad; body-wall 1'5 millim. thick at sides ; mouth probably about the same as in the normal forms (most of it has been broken away). The microscopic characters are tabulated below. Var. crassior, however, has the triradiates much larger (maximum size of ray of those of caminus='6o by "075 millim.), the angles are all equal, not paired. The acerate is apparently longer; and the rays of the quadriradiates are straight, instead of the laterals and the apical being bent (as in caminus). Perhaps therefore crassior constitutes another species ; but in the face of the single imperfect specimen it will be well to await better information. |
