454 coLLBCTioirs feom Melanesia. 



ECHINODICTYUM. 



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

 Dictyocylindrus, Carter, pars, nee Sowerbank. 



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

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

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

 Naxdo, 1833, Schmidt, 1862, Bowerbank, 1864). The spiculation, 

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

 two genera (B. viminalis, Schmidt, and D. Jiispidus, Montagu) agree 

 essentially. Bowerbank has placed in his genus, besides typical 

 jRaspailice, species of Aaios {D. dentatus) and Axinella (D. setosus). 

 Carter has placed in the genus species (J), ladniatus and pyJcei) of an 

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

 spined cylindrical instead of a spined acuate echinating spicule, as 

 in EcJiinodictyum, which is thus further approximated to Maspailia. 

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

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

 then be distinguished from Baspailia only by a more robust habit 

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



EcHiNODiciTUM, diagn. emend. Sponges erect, cup-sha'ped or 

 ramose. Skeleton formed of spicules united into distinct fibres. 

 Prom 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-Paciflc region. 



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

 p. 114, S. W. Australia, and Dictyocylindrus ladniatus and pylcd, id., 

 must be referred to this genus. 



83. Echinodictyum bilamellatam. 



Spongia bilamellata,' Lamarck, Ann. Mm. Hist. Nat. xx. p. 434. 

 Echinodictyiim bilamellatum, Ridley, Journ. Linn. Sue, Zool. xv. 

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



A dry specimen, very closely resembling in its external characters 

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

 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 miUim.; smaller acerate, about 

 •17 to '24 by '0095 miUim. ; spined echinating cylindrical, '099 to 



Indian species Eciyon sparsus, appears to me to be speeifioallj distinct both from 

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

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

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



