OCR Text |
Show 1881.] THE SURVEY OF H.M.S. 'ALERT.' Ill generally less thick than in our species. When the external characters of this Sponge are known, it may perhaps prove to be identical with our species. Of several Sponges which have almost identically the same spicule may be mentioned:-Spongia arborescens, Lamarck, said to inhabit the "seas of America;" Chalina limbata, Bowerbank (Montagu?), and C. gracilenta, Bowerbank, Britain. The latter is probably the nearest-allied species which has been described, but differs in having the spicules much more numerous in the fibres, in having a less elaborate intermediate set of fibres, in the slightly inferior length (about "08 millim.) of the spicules, and the coating habit of growth. The specific name has been given to it in honour of the discoverer, Dr. R. W . Coppinger, who has, by the richness in species of this valuable collection, and by the good condition in which he has sent the specimens, made so important an addition to our knowledge of the Sponge-fauna of a region in which it has been hitherto almost entirely uninvestigated. SIPHONOCHALINA FORTIS, sp. n. (Plate X. fig. 3.) Erect, tubular. Tube dilated in some parts. Mouth single, unfringed. Main skeleton composed of a set of primary horny fibres radiating from inner to outer surface, projecting from the latter by short points, diameter from "14 to '25 millim.; and of a secondary set at right angles to the former, diameter from '07 to '14 millim.; both sets amber-brown in colour. Primary fibres cored by an axial series of proper spicules, 3 to 5 spicules broad, often somewhat scattered; secondary fibres cored by an axial series of proper spicules, 1 to 2 spicules in breadth. Dermal skeleton composed of a rectangular network of pale-brown fibre from "0095 to '025 millim. in diameter, extending between points of primary fibres, generally cored by 1 to 2 series of spicules. Parenchyma transparent, almost colourless. Spicules of one kind in skeleton and flesh, viz. smooth acerate, tapering to sharp points from about 2| diameters from the ends; size '07284 by '00739 millim. Examined. Dry and by mounting in balsam. External Characters. The single specimen consists of a tube which has been torn from a larger mass, and might well, when perfect, have had the general form of the specimen figured1 as Gallyspongia bullata by Duchassaing de Fontbressin andG. Michelotti, and referred by Schmidt2, with great probability, to a species of Siphonochalina. The tube is 40 millims. in height, 17 millims. at its greatest, 11 millims. at its smallest diameter ; it has somewhat the outline of an hour-glass, being constricted to 11 millims. at about 10 millims. from the mouth ; it is circular, with walls varying from 1 to 4 millims. thick. It has lost most of its sarcode and much of its dermal skeleton. The edge of the mouth is level all round, and shows no trace of a fringe of projecting fibres. Vents. These are probably represented by the single mouth. 1 Spong. Mer. Caraib., pi. x. fig. 5. J Spong. atl. Geb. p. 33. |