ZOOLOaY OF FERNANDO NOEONIIA. 



507 



projecting from a commou cavity. Colour wMte. Entire speci- 

 men about an inch long, and | of an inch in diameter (1 X | X | 

 inch) ; broken out on one side, if not the point of attachment. 

 The uppermost or principal division ending in a peristomatous 

 mouth, which can only be seen with a microscope, hence to the 

 unassisted eye looks " naked " ; -^^ in. in diameter. The same 

 on the summit of each inflation, but reduced to the size of a pin's 

 head. Surface of the body smooth, composed of iutercrossing 

 arms of quadriradiate spicules only, between which are the pores. 

 Vents as just described, leading into a general cloacal cavity 

 corresponding in its inflations with those of the body. Surface 

 of the cloaca scattered over with holes of very diff'erent sizes, 

 very irregularly situated in a layer of minute quadriradiates 

 whose fourth arm is much smaller than the rest, curved towards 

 the oral orifice and projecting plentifully above the surface of 

 the cloaca. The spicules of three kinds, viz. 3-radiate, 4- 

 radiate, and linear cylindrical acerate. 



Wall of the body about j\ in. in diameter, composed of. 

 three layers of spicules, viz. : — 1, consisting of comparatively large 

 quadriradiates whose shaft projects inwards and whose otlier 

 three arms are spread out horizontally over the surface; arm 

 about by 3-J-g- in. in its greatest diameters ; 2 (the middle 

 substance of the wall), consisting of 3- and 4-radiates mixed 

 irregularly, whose arms are about the same size as that of the 

 quadriradiates of the first or external layer; 3, or internal 

 layer, forming the surface of the cloaca, and consisting of minute 

 or infinitely smaller quadriradiates, whose shafts are directed 

 outwards ; the other two arms horizontal, and the fourth, or 

 " t^pine " as it has been called, which is much the smallest, pro- 

 jecting above the surface in the way mentioned. Peristome con- 

 sisting of palisading spicules about -^^^ in. long, very fine and 

 straight with abruptly pointed ends, crossed and kept in position 

 by the spreading arms of the quadriradiates of the third, or cloacal, 

 layer, here much enlarged. Wall permeated by branched canals, 

 which commencing on the pores on the surface end in the holes or 

 apertures on that of the cloaca. 



Log. Island of Fernando Noronha. 



39. GrEODiA. — Fragments of skin and body-aubstancc. Same 

 as No. 11, &c. 



