454 COLLECTIONS FROM MELANESIA. 



ECHINODICTYUM. 



Echinodictyum, Ridley, Journ. Linn. Soc, Zool. xv. p. 493. 

 Dictyocylindrus, Carter, pars, nee Bowerbarik. 



There can be no doubt that Schmidt is right in identifying his 

 (Nardo's) genus Raspailia with Dictyocylindrus of Bowerbank, and 

 in superseding the latter name on grounds of priority (the dates are, 

 Nardo, 1833, Schmidt, 1862, Bowerbank, 18G4). The spiculation, 

 outward form, and skeleton-arrangement of the type species of the 

 two genera (R. viminalis, Schmidt, and D. hispidus, Montagu) agree 

 essentially. Bowerbank has placed in his genus, besides typical 

 Raspailice, species of Axos (D. dentatus) and Axinella (D. setosus). 

 Carter has placed in the genus species (D. laciniatus and pyhei) of an 

 erect branching habit, somewhat like some Raspailice, but with a 

 spined cylindrical instead of a spined acuate echinating spicule, as 

 in Echinodictyum, which is thus further approximated to Raspailia. 

 A slight enlargement of this genus, by admitting species which have 

 the setaceous acuate, will, I believe, meet the requirements ; it will 

 then be distinguished from Raspailia only by a more robust habit 

 and by having the fibre exclusively composed of acerate spicules : — 



Echinodictyum, diagn. emend. Sponges erect, cup-shaped or 

 ramose. 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 acuate (single-pointed) spicules may also be inserted 

 upon the fibre, projecting from it at acute angles. Spicules com- 

 posing fibre exclusively smooth, acerate (doubly pointed). No 

 special flesh-spicules. 



Distribution. Indo-Pacific region. 



Echinonema vasiplicatum, Carter, Ann. & Mag. Nat. Hist. 1882, ix. 

 p. 114, S.W. Australia, and Lictyocylindrus laciniatus andpyJcei, id., 

 must be referred to this genus. 



83. Echinodictyum bilamellatum. 



Spongia bilamellata, Lamarck, Ann. Mas. Hist. Nat. xx. p. 434. 

 Echinodictyum bilamellatum, Ridley, Journ. Linn. Soc, Zool. xv. 

 p. 493, pi. xxviii. figs. 1-6. 



A dry specimen, very closely resembling in its external characters 

 the one which I described (I. c.) from N.W. Australia, but not so well 

 preserved. It differs somewhat from previously known specimens 

 in 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 to 



Indian species Ectyon sparsus, appears to me to be specifically distinct both from 

 Dr. Gray's and the present species for two reasons, viz. (1) the presence in it 

 of a smaller grapnel-spicule with spined shaft ; and (2) the apparent absence 

 of the tibiella. I propose the name Acarmts carteri for the West-Indian form. 



