48 Mr. H. J. Carter on 



of radiate spicules intercrossing each other, through which the 

 curved sickle-shaped acerates project. Pores in the inter- 

 stices of the dermal reticulation. Vents in plurality, scattered 

 over the surface, at least six in number, each provided with a 

 conical, glistening peristome, which contrasts strongly with 

 the grey colour of the body, and all opening into a single 

 cloaca, which is narrow, corresponding in shape with that 

 of the specimen ; in width about the same as the thickness 

 of the wall ; holes of the cloaca large and subcircular, sepa- 

 rated from each other by variable distances in proportion to 

 the width of the intervening spicular framework of the cloaca, 

 presenting within their borders respectively one or more 

 circular openings which appertain to the structure of the wall. 

 Structure of the wall no longer presenting any trace of radial 

 chambering beyond the parallelism of the long shafts of sagit- 

 tal triradiates which successively following each other chiefly 

 from within outwards traverse a simply clathrous cancellated 

 sarcode, the shafts of the larger or inner triradiates being met 

 by those of the smaller ones descending from the surface. 

 Spicules of two kinds, viz. acerate and triradiate : — 1, acerates 

 of two forms, viz, one thin, straight, cylindrical, glistening, 

 and silk}^, sharp pointed at each end j and the other thick, 

 unequally fusiform, that is the outer portion being thicker 

 than the inner one, and so curved in the outer part as to be 

 almost sickle-shaped, about 150 by 2-6000ths in. ; 2, triradi- 

 ates, small and large, the latter averaging 100 by 6-6000ths 

 in. in the shaft, and 40 by 4-6000ths in. in the arms respec- 

 tively, which are spread out in a sagittal manner. No. 1, in 

 its thin form, confined to the peristomes, and in its thick one 

 to the surface generally, where it is curved towards the mouth, 

 the larger or free end externally and the other attenuated and 

 imbedded halfway through the wall ; no. 2, the triradiates 

 in their smaller forms chiefly confined to the spicular structure 

 of the surface and that of the cloaca respectively, and the 

 large ones to the wall, where the largest, whose measurements 

 have been given, have their heads in the cloaca and their 

 shafts directed outwards to meet the smaller ones which come 

 from the surface. No quadriradiates were seen. Size of speci- 

 men 7-l2ths in. long, by 5-12ths in. transversely. Two 

 smaller ones growing from the base give the " social " cha- 

 racter. 



Obs. This specimen may be recognized by the number of 

 small glistening peristomes scattered over the surface, the 

 presence of the large sickle- shaped acerates of the surface, and 

 tlie absence of the quadriradiate. 



