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

—;BPONGIIDA. 431straight, sharp, slender, about -002 millim. long at head, wherethey are closely aggregated, gradually decreasing in size andnumbers towards point, where they cease entirely ; size of spicule•1 to -17 by -0063 to -0079 millim. (2) Hastate cylindrical orsubacerate, smooth, of almost uniform diameter from centre towithin two diameters of ends, whence it tapers to a sharp pointsize "2 by -0042 millim. Flesh-spicule, (3) Equianchorate ; tridentate,with stout, strongly backwardly curved shaft -0026 millim.in diameter ; lateral arms of heads subtriangular, about '0063millim. long, the middle of the margin of the arm conspicuouslyfolded inwards ; the middle arm narrow, oblong, about '0032 millim.long ; length of spicule -025 milHm.Hah. Port Jackson, to 5 fms.The entire " stock " or head, of which the single well-preservedspirit-specimen consists, is 42 milhm. (1| inch) in height by 40in greatest diameter ; the individual branches may be as much as9 millim. in diameter at their broadest palmate part. I am underthe impression that this is the species alluded to by Mr. Carter(Z. c.) as Halklinndria j'ltimosa, from Kerguelen Island. It differs,however, in spiculation from the typical form of that British speciesin having the shaft of the anehorate about twice as thick andin the longer and slenderer hastate spicule ; the difference betweenthe anchorates is perceptible even under a low magnifying-power.It is, however, nearly allied to both it and Myxilla fictitia ofBowerbank, and to some Mediterranean Myxillce of Schmidt.I add the measurements of the spicules of what is probably thetype specimen oi UaJichondria (Microciona, Hk.) 2^iumosa, Mont,, forcomparison :1. Spined acuate, '16 by -0063 millim.2. Hastate acerate (hastate only at one end), -17 by -0063millim.3. Equianchorate, -016 millim. long, shaft "0013 millim. indiameter.Mr. Carter places species of this nature in a new Group, calledPlumohalichondvhvi (Ann. & Mag. Nat. Hist. 1875, xvi. p. 144, and1880, vi. p. 39), as being distinguished by their habit and their angulated,not " naviculiform " anehorate ; but his genus Pluniohalichondria{op.cit.1876, xviii. p. 236) must be carefully distinguishedfr(»m this similarly named Group, for it is described as possessing anaviculiform anehorate.CRELLA.Crella, Gray, P. Z. S. 18G7, p. 521.Cribrella, ISchmidt, Adr. Meer. p. 69.Schmidt's generic name was already in use for a genus ofAsteridean Echinodermata (L. Agassiz, 1835, Mem. Soc. iSci. Neufchatel,i. p. 191). Dr. Gray therefore very properly altered it.The present species, although the first assigned to the genua from