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Show 1881.] THK SURVEY OF H.M.S. 'ALERT.' 109 The great regularity of its skeleton, and its distinction into two kinds of fibres differentiates it from Dendrospongia, Hyatt, as well as from the other known species of its genus. The characters of the axial fibre-substance distinguish it from Verongia, Bowerbank. Order PSAMMONEMATA, Carter. H I R C I N I A HISPIDA, Lamarck (sp.). Spongia hispida, Lamarck, Ann. Mus. Hist. Nat. xx. p. 452. External Characters1. The single (spirit) specimen agrees fairly well with the characters assigned to this species by Lamarck {I. c), and with the specimen of the species already in the British Museum. It being, however, evidently young, the branching character is no more than indicated by the extension outwards of a rounded lobe from each side ; and as it is a well-preserved spirit specimen, the small foramina of Lamarck's description and of the dried specimen are wanting. It is sessile by a broad base, and suboval in outline, the long axis extending from side to side. Surface uneven, rendered coarsely hispid by the projecting ends of the primary skeleton-fibres, arranged at intervals of from "5 to 175 millim. (to 2 in the dried state). Colour in spirit dark brown, slightly rufous; of dry skeleton, pale yellow-brown. Vents few, round ; diameter in spirit 1"5 millim., in dried specimen 2 to 3*5 millims. Pores 1 Skeleton. Consists of a set of stout primary, generally sand-cored, fibres running outwards from the interior, each terminating at right angles to the surface in one of the surface-papillse. These are connected by a secondary set, consisting of an irregular network of much finer, uncored fibres, meeting the primary fibres at acute angles, and forming by their branching and anastomosis irregularly diamond-shaped meshes. Surface network formed by secondary fibres connected with the interior secondary-fibre network, and laterally with the apices of the primary fibres. Primary fibres cored by coarse foreign bodies, which are enveloped by pale-yellow horny matter, but which generally occupy all the fibre except a slight external film, and cause it to bulge largely at the sides; diameter from -0507 to "235 millim. in the spirit, from "038 to *0834 in the dry specimen. It should be noted with regard to this discrepancy that the foreign bodies in the latter are much smaller than in the former, and being many of them sponge-spicules, which protruded from the fibre, were not included entirely in the estimate of the diameter as given here. There is considerable irregularity as to whether the fibre is cored throughout or not in this specimen, which may be due to the reason suggested by Hyatt2 for a similar fact observed in Carteriospongia otahitica, viz. the relatively smaller amount of accessible material for the core in the one case. Secondary fibres obscurely striated, the external lamina? denser than the internal ones, 1 All the characters are taken from the spirit specimen, deviations in the dry one being noticed. 2 Mem. Bost. Soc. ii. pt. iv. p. 541. |