278 Mr. H. J. Carter on the SarcohexactmelUd Sponges. 



position in other similar sponges, and of those which still 

 remain in Labaria^ it should be interspersed among the 

 plumose spicules, while No. 5 may be dispersed throughout 

 the body generally. 



Average size of the largest spicules of each kind : — In No. 

 1 the length of the arms varies in the same spicule, so that 

 the longest shaft and longest arm generally may be set down 

 at about 3-12ths inch long, with a thickness at the base of 

 about 2o-1800ths inch. No. 2 in its longest form appears to 

 be about two inches, with a maximum thickness in the shaft 

 of about 7'1800ths inch ; while the spread of the double hook 

 at the free extremity in the smooth form is about 38-1800ths, 

 and in the spiculiferous one about 17-1800ths inch. The 

 short stout form of No. 3 (the surface-spicule) averages about 

 10-1800ths long, and the slender variety about 15-1800ths. 

 No. 4 in its largest size is about 15-1800ths long, and No. 5 

 (the microscopic spicule) about 8-1800ths inch in diameter 

 from end to end of its arms. Size of specimen : — Greatest 

 horizontal diameter outside If^ths inch, vertical l-^^ths 

 inch ; diameter of outlet of basal tuft y^ths inch ; diameter 

 of outer margin of concavity 1-i^ths inch ] greatest diameter 

 of concavity l|^ths inch ; thickness of wall of cup -^ths 

 inch ; diameter of basal tuft of spicules about ^ths inch. 



Hah. Marine. 



Loc. Unknown, from Singapore. 



Ohs. In the above description nothing has been said about 

 the position of the "vents," chiefly from the fact that there 

 is no appearance of any distinct ones in the concavity of the 

 sponge ; and although 8-10 holes appear at irregular distances 

 round the outer border of the margin of the cup, and about 

 twice as many scattered over its outer surface or convexity, 

 still, from these having been artificially filled with bristle-like 

 fragments of long stout spicules from another sponge, for the 

 purpose hereafter mentioned, I am by no means certain that 

 these holes are not artificial. From analogy one would feel 

 inclined to say that they are artificial ; for, as a rule, into the 

 concavity (erroneously termed " cloacal "), whether cup-like or 

 tubular (in the great " Neptune's cup," in which a child 

 might sit down, or in that of the calcareous sponge Grantia 

 ciliata^ into which the head of a pin can hardly be inserted), 

 the vents chiefly open and the pores are chiefly outside. 

 As instances of this in the sarcospiculous Hexactinellidag, 

 with which we are now chiefly concerned, Holtenia Garpenteri 

 and Rossella velata, W. Thomson, and Crateromorpha Meyeri 

 and Bossella philippinensis^ Gray, if not also Pheronema 

 Anmv, Leidy, and P. Gmyi, Kent, may be cited. In Meycrina 



