Sponges from the Atlantic Ocean. 211 



apical (fig. 3, a), where it is surrounded by the fringe of long 

 spicules just mentioned, while smaller vents (fig. 3, c) are scat- 

 tered over the surface generally. Pores not seen. Internal 

 structure massive, permeated by the excretory system of canals, 

 which has its chief vent at the apex ; charged with skeleton- 

 and flesh-spicules, and surrounded by a cortical layer chiefly 

 composed of the former, whose projecting ends give the villous 

 surface (fig. 3, c?). 



Spicules of two kinds, viz. skeleton- and flesh-spicules. 

 Form of skeleton-spicule, of which there is only one, smooth, 

 acerate, fusiform, finely pointed, and nearly straight ; average 

 largest size 27 by |-1800t]i of an inch in its greatest diameters 

 (PI. XV. fig. 34), that of the fringe round the apex much 

 longer, viz. l-24th inch. Flesh-spicule equianchorate, in which 

 the lateral arms are so blended with the shaft as to convert the 

 whole into a flattened plate, of an hourglass- or guitar-shape, 

 constricted in the centre and round at the ends (PI. XIII. 

 fig. 4,ahc), bordered inside throughout by a fringe directed in- 

 wards towards the shaft (fig. 4,^), leaving a trapezoidal, clear 

 area opposite the constriction, and a narrow, obovate one at 

 each end (fig. 4,bc) : anterior arm at each end flat, expanded 

 into a circular or obtuse, thin, elliptical plate, presenting the 

 same kind of fringe round its margin, directed inwards, and 

 leaving, as in the shaft, a transparent ovate area in the centre 

 (fig. 4, b) • anterior arm equal in width to the end of the shaft &c., 

 to which it is parallel transversely, but longitudinally inclined 

 from it at an acute angle beginning at the end (fig. 4, a), where 

 it is united to the shaft by a short falx (fig. 4, /), opposite to 

 which is a large, clear, circular tubercle (fig. 4, e) : average 

 length of largest form 16-6000ths inch ; widest part 6-6000ths ; 

 constricted part 3-6000ths. Size of entire specimen about 6 by 

 4-12ths of an inch in its largest diameters. Fringe of spicules 

 round the apex l-24tli inch broad. 



Uab. Deep sea. 



Loc. Atlantic Ocean, off the N.W. coasts of the British 

 Isles. 



Obs. The jar containing this, with a specimen of Podospongia 

 Lovenii^ Bocage, one of Desmacella 'pumilio^ Schmidt, and a 

 fragment of an Hexactinellid sponge {AskonemaT) bears no 

 label. It is remarkable for the form of the anchorate spicule, 

 which, but for reference to that of Halichondna incmstans^ 

 above given, is so modified in form that it could hardly be 

 otherwise understood. Although the average largest size of 

 this spicule is figured, it is present of all intermediate sizes down 

 to an embryonic form not more than 2-5000ths inch long, in 

 which the outlines alone of the hourglass-shape can be distin- 



