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

SPONGIIDA. 453strongly recurvate ; size of spicule '07 by -0095 millim. : veryabundant on the fibre. (4) Navicular equianchorate of sarcode,shaft slender, almost straight ; length of spicule 'OlS millim.Hah. Prince of Wales Channel, Torres Straits, 5-7 fms.Gray, P. Z. S. 1867, p. 544.ACARNUS.Acarnia is used as a generic name in an earlier part (torn.cit. p. 515) of the same paper as that in which Dr. Gray describedAcarnus; but it has not come into general use, otherwise theessential agreement in form between the two words would necessitatethe suppression, on that ground, of the later one. A carefulcomparison of the grapucl-spicule, which characterizes the genus,with the spined cyliudricals of Clathria and EcliinoclicUjum showsthat the affinity of the sponge is with these genera rather than withthe "Tethyadaj" of Dr. Gray, as held by him, or with the " Espcriadse,"as supposed by Mr. Carter (Ann. & Mag. Xat. Hist. 1871, vii. p. 274).A. innominatus. Gray* (I. c), besides the remarkable 4-hookedgrapnel-like spicule and the acuato (not cylindrical, as stated byGray, I.e.) form wbich characterize the main skeleton, possesses—as Ihave been able to ascertain by an examination of a mounting madeby Dr. Bowerbank, who was the first to figure and describe thesespicules (Mon. Brit. Spong. i. figs. 73-76, 292), which Dr. Gray afterwardsembodied in his description of the species—also a tricurvate(figured by Bowerbank) and an equianchorate flesh-spicule ; theformer about "13 by '0042 millim. in dimensions, the latter •OK) to•024 millim. long ; also a tibiella, measuring about '28 by -0045(shaft) or -0063 (head) millim.82. Acarnus ternatus. (Plate XLII. figs. 6, b'.)From a mounting which the Museum owes to the liberality of Dr.John Millar, and from the spirit-specimen inthe present collection,we learn that in this new species the acuate spicules are imbeddedin a reticulate horny skeleton of a pale salmon-red colour, and not,as usual, yellow. The grapnel has but three hooks, and the tibiellaThe other spicules agree withhas the shaft only -003 millim. thick.those of A. innominatus. The largest of the present specimens isabout 65 by 25 millim. (2| inches by 1 inch), and forms a clathrousstructure of round soft anastomosing trabeculoe which are about3 millim. in diameter. Colour in spirit reddish brown. Severalspecimens occur in the present collection.Hab. West Island and Prince of Wales Channel, Torres Straits,7 fms. ; bottom sand and coral.Distribution. Bombay? (coll. Brit. Mus.).* Mr. Carter gives reasons (l. c.) for bis supposition that the West Indiesare the home of this species; the specimen, however, to which he appeals insupport of this view, viz. that attached to the base of a specimen of the West-