OCR Text |
Show 116 ZOOLOGICAL COLLECTIONS M A D E DURING [Jan. 4, Examined. In spirit and by mounting in balsam. External Characters. Sessile, forming a beehive-shaped mass about 18 millims. deep by about 50 millims. long and 36 broad, growing on the surface of a large flexible worm-tube. Surface curved^both actually and relatively to its base, so that the thickness of the Sponge at the edges is almost nil. Surface slightly irregular, owing to depressions between the ends of the skeleton-fibres, covered externally by a dirty-white dermis of the same colour as the fibres. Surface of dermis smooth. Vents 1 Pores apparently represented by oval openings, from •633 to -16 millim. in diameter, occurring in groups. Fibre resembling that of Desmacidon fruticosum, Johnston, in amount of soft material, except at base, where the spicules lying in the centre occupy only about half the diameter of the fibre, and give it a strongly Chalinoid appearance. Spicules lying parallel in the fibre, projecting from it only at the dermis. Soft material of fibre granular, yellowish, subopaque, not resembling ordinary horny fibre. Number of spicules in diameter of fibre varies from about 15 millims. in larger to 3 or 4 in small lateral fibres. Parenchyma. Yellowish white, granular, adhering to fibres. Dermal Membrane. Yellowish white, granular, in some parts possessing muscular or other fibres, apparently arising from beneath it. Skeleton-spicule. Of one kind, acuate, slightly bent, tapering gradually from a well-rounded head to a sharp point. Size '577 by -01267 millim. Flesh-spicule. None. Hab. Sandy Point, 7-10 fathoms ; on large worm-tube. Obs. The strongly ceratinous character of the base of the fibres, the absence of fistulse, and the absence of dense spicular axes from which the fibres should radiate, all tend at first sight to separate this species from the genus Ciocalypta, and, in fact, exclude it from that genus, if we limit it to forms included by Dr. Bowerbank's diagnosis ; but the general structure of the fibre and the mode of termination of its outer extremity, together with the general agreement in the form of the spicules, ally it. too closely to C. penicillus and C. leei to allow of a distinct generic appellation at this time, especially as the method of growth suggests that it may be merely a young or sessile form of a species closely allied to C. leei. The proportions of the skeleton-acuates are :- C. penicillus, Bowerbank. Britain. "6035 by "02058 millim. C. leei, Bowerbank. Britain. *57 ,, "019 „ C calva, Magellan. -577 „ '01267 „ C. tuberculata1, Carter, is closely allied to these, but has a skeleton-spicule '023223 millim. iu diameter. The specimen is remarkable for containing in its dermis a number of spicules belonging to Esperia magellanica-. 1 Ann. & Mag. Nat. Hist. ser. 4, xviii. p. 235. - Cf. Journ. Linn. Soc. (Zool.), xv. p. 149.- |