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

—454 COLLECTIONS FROM MELAHESIA,ECHINODICTYUM.Echinodictyum, Ridlcfj, Journ. Linn. Soc, Zool. xv. p. 493.Dictjocylindrus, Carter, pars, nee Boicerbanh.There can be no doubt that Schmidt is right in identifying his(Nardo's) genus Easpailia with Dictyocylindrus of Bowerbank, andin superseding the latter name on grounds of priority (the dates are,Nardo, 1833, Schmidt, 1862, Bowerbank, 1864). The spiculation,outward form, and skeleton-arrangement of the type species of thetwo genera (-K. vimiaalis, Schmidt, and B. liispidus, Montagu) agreeessentially, Bowerbank has placed in his genus, besides typicalRaspailuf, species of Axos {D. dentatus) and Axinella (D. sctosus).Carter has placed in the genus species (D. Ictciniatus and pylcei) of anerect branching habit, somewhat like some Kasjxtilice, but with aspiued cf/Iindrical instead of a spined aeuate echinating spicule, asin EcMnodictyum, which is thus further approximated to Raspailia.A slight enlargement of this genus, by admitting species which havethe setaceous aeuate, will, I believe, meet the requirements : it willthen be distinguished from Raspailia only by a more robust habitand by having the fibre exclusively composed of acerate spicules :EcHiNODiCTTrM, diagn. emend. Sponges erect, cup-shaped orramose. Skeleton formed of spicules united into distinct fibres.From the fibres project at right angles short, strongly spined,cylindrical spicules, tapering from their attached ends ; long,slender, smooth aeuate (single-pointed) spicules may also be insertedupon the fibre, projecting from it at acute angles. Spicules composingfibre exclusively smooth, acerate (doubly pointed). Nospecial flesh-spicules.Distribution. Indo-Pacific region.Echinonema vasiplicatum, Carter, Ann. & Mag. Nat. Hist. 1882, ix.p. 114, S.W. Australia, and iJictyocylindrus laciniatus and p?/^-a, id.,must be referred to this genus.83. EcMnodictyum bilamellatum.Spongia bilamellata, Lamarck, Ann. Mus. Hist. Nat. xx. p. 434.Echinodictyum bilamellatum, Ridley, Journ. Linn. 8oc., Zool. xv.p. 493, pi. xxviii. figs. 1-6.A dry specimen, very closely resembling in its external charactersthe one which I described {I. c.) from N.AV. Australia, but not so wellpreserved. It diff'ers somewhat from previously known specimensin the proportions, though not in the form, of its spicules, viz. :Larger acerate, about -35 by "018 millim.; smaller acerate, about•17 to -24 by '0095 millim. ; spined echinating cylindrical, -099 toIndian species Ectyon sjjarsus, appears to me to be specifically distinct both fromDr. Gray's and the present species for two reasons, viz. (1) the presence in itof a smaller grapnel-spicule with spined shaft ; and (2) the apparent absenceof the tibiella. I propose the name Acarnus cartcri for the West-Indian form.