Report on the zoological collections made in the Indo-Pacific Ocean ...

SPONQIIDA. 615near centre to sharp points ; size -32 by -0063 millim. (in axis ofouter extremities of primary fibres, and loose in the meshes of theskeleton). (4) Tricurvate acerate, smooth; the curves bold; taperingto sharp points ; size -076 to -12 b^ -0032 millim. (in sarcode).(5) Equianchorate, shuttle-shaped, shaft slender, slightly and graduallycurved, palms each about one third the total length of the•spicule ; length -025 millim.Hah. Marie Louise Island, Amirante group, 17 fms.: bottom coral.The specimen on which this species is based coats continuouslyfor a distance of 100 millim. (4 inches) most of the circumferenceof a stem (probably algal) 3 millim. in thickness. The surfaceof S^iongia vulpina, Lamarck, in the Museum at the Jardin desPlantes, Paris, decidedly recalls this sponge ; but that species istall, stipitate, and arborescent, with a superficial spicular incrustation,and hence is rather referable to RhapJiidopJilus than Clathria ; itseems to want the tricurvate acerate spicule of the present species.One remarkable point about the species is the unusually greatproportion of horny matter to spicules in the fibres. This is alsoshown in Tenacia dathrata, Schmidt, of the W. Indies, which, besidesits clathrous habit, differs from this species mainly in the very coarsehorny fibre, the considerably superior dimensions of the smoothacuates, and the rather clumsy form of the spined echinatingspicules.37. Acarnus tematus.See Part I., p. 453, of this <strong>Report</strong>.A young specimen. The tricurvates are somewhat shorter,thicker, and more strongly curved than in the Australian specimens.Hab. He des Neufs, Amirante Islands, 15 fms.ECHINONEMA, Carter.This genus was nominally established in 1875 (Ann. & Mag. N. H.1875, xvi. p. 185), in Mr. Carter's " Notes Introductory to the Studyand Classification of the Spongida," by the insertion of the words" Ediinonema typicum, C, MS.," under the Group Pluriformia,Family Ectyonida, of the Order Echinonemata; but its characters werenot made known until 1881 {op. cit. 1881, vii. pp. 378-380), whenMr. Carter somewhat briefly described two species under this name,viz. E. typkmn and E. anchoratum, without, however, giving anydefinition of the genus. I have been able to examine a considerablenumber of the specimens thus identified by Mr. Carter, and findthem to be nearly allied to IthaplMoplilus of Ehlers (Espersch.Spong. pp. 19,31) and to Clathria, Schmidt, having the same generalcharacter of spiculation and arrangement of the skeleton as thesegenera, but differing from Clathria in having a non-fibrous andpurely spicular cortical layer, composed of acuates or spinulateswith their points directed outwards, and while agreeing withEhapUdophlus in this point, differing from it in the possession (not