ZOOLOGY OF FERNANDO NOKONHA. 5o7 



projecting from a common cavity. Colour white. Entire speci- 

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

 inch) ; brokeii out on oue side, if not the point of attachment. 

 The uppermost or principal division ending in a peristomatous 

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

 unassisted eye looks " naked " ; y% in. in diameter. The same 

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

 head. Surface of tlie body suiooth, composed of iutercrossing 

 arms of quadriradiate spicules o«Z_y, between which are tlie pores. 

 Vents as just described, leading into a general cloacal cavity 

 corresponding in its inflations with thoye of the body. Surface 

 of tlie cloaca scattered over with holes of very diftereut 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 other 

 three arms are spread out liorizoutally over the surface; arm 

 about -^K by -^^-g iu. 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 minicte 

 or infinitely smaller quadriradiates, whose shafts are directed 

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

 "spine" 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 tliird, 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. 



Loc. Island of i'ernando Noronha. 



39. G-EODiA. — Fragments of skin and body-substance. Same 

 as No. 11, &c. 



