Sponges from the Atlantic Ocean. 389 



(fig. 20,^). Vent single, apical, surrounded by a cone of long 

 linear spicules (fig. 20, e). Internal structure densely spicu- 

 lous, compact, suberose, hard and firmly continuous with the 

 dermal layer ; composed of spicules radiating in bundles from 

 the centre (which is light-coloured, on account of the compara- 

 tive absence of sarcode) to the circumference ; followed by a 

 zone of softer substance, in which the ova appear to be 

 specially developed, limited by a layer of compressed cavities, 

 forming part of the excretory canal-system, into which the ova 

 fall probably, when matured, and thus gain their exit. This, 

 again, is followed by a subdermal zone, in which the bundles 

 of spicules appear to be finally divided into lashes, each lash 

 going to a punctum or pore on the surface ; last of all comes 

 the dermal zone itself, which is composed of a layer of spi- 

 cules corresponding in the lightness of its colour with that 

 of the centre, probably also from the comparative absence of 

 sarcode ; the whole traversed by the excretory canal-system, 

 which opens at the single vent mentioned (fig. 20, d). Stem 

 similarly composed. Sarcode of the internal substance yel- 

 lower than that of the dermis. Spicules of two kinds, viz. 

 skeleton- and flesh-spicules. Skeleton-spicules of two forms, 

 viz. : — 1, large, acerate, fusiform, smooth, finely pointed at 

 each end and nearly straight, about 37- by ^-1 800th inch 

 (PI. XIV. fig. 20, ^, and PI. XV. fig. 38) ; 2, small or sub- 

 skeleton, short, subacuate or subacerate, fusiform, slightly 

 curved, thickly and irregularly sjnned, spines short, sharp, 

 conical, vertical, 11- by l-1800th inch (fig. 20, k). Flesh- 

 spicule of one form only, viz. equianchorate, with slightly 

 curved bow-shaped shaft and falcate spreading arms, webbed 

 up nearly to the points (fig. 20, ?, 77i). The skeleton-, mixed 

 with a few of the spinous spicules, chiefly make up the struc- 

 ture of the sponge generally, while the cone at the apex of the 

 head (fig. 20,/) is formed by a projection of the smooth long 

 acerates alone; each "lash" of spicules also, after traversing 

 the subdermal zone, ends by slightly protruding beyond the 

 apex of its respective punctum, while the dermal layer of the 

 short spiniferous acuates is arranged in whorls round the 

 puncta, whose apices are thus traversed by the lash of skeleton- 

 spicules respectively ; and here alone the flesh-spicules (ancho- 

 rates) appear to be congregated. Size of specimen about 

 ll-24ths inch long by 4-24ths in the broadest part, i. e. of the 

 head. 



Hob. Marine, attached to small pebbles. 



Loc. Atlantic Ocean, in 290 fathoms, about Q6 miles 

 N.N.W. of the Orkneys. 



Ohs. There is but one entire specimen of this little sponge. 



