504 Mr. H. J. Carter on 



mentioned. Colour sponge-brown when fresh, when dry- 

 dark grey. Surface even, uniformly reticulate, interstices 

 about l-120th in. in diameter. Pores numerous, passing 

 through the wall of the hollow thread. Vent single, tubulated, 

 at the summit of the specimen, composed of a thin, cylindrical 

 extension of the walls of the tubulation , which at this part 

 opens into it by a plurality of holes, and thus enters into its 

 composition. No defined cloacal dilatation. Structure already 

 stated, composed of the same kind of staple thread as 0. cavata, 

 but smaller and more compact in its reticulation ; wall 

 of the tubulated thread very thin and skeletaliy composed of 

 a single layer of triradiate spicules held together by sarcode, 

 and lined by the softer parts, which here also appear to 

 consist chielly of a layer of spongozoa in juxtaposition, that 

 is without being gathered into the form of avnpullaceous 

 sacs, together with a remarkable quantity of those organs 

 which consist of nucleated cells respectively surrounded by an 

 abundance of glistening spherical granules, which Hackel has 

 figured and named "nuclei" (Kerne) of the syncytium, as 

 before stated. Stem apparently an extension of the tubulated 

 thread, but more solid. Spicules of one kind only, viz. tri- 

 ro.diates of different sizes, but for the most part equiarmed and 

 equiangulated, intercrossing each other on the surface so as 

 to give the interstices of the reticulation here a polygonal 

 border ; spicules more plentiful and larger than in C. cavata, 

 ray of the larger ones averaging 42 by 5-6000ths in. in its 

 greatest dimensions. Size of individual, of which there are 

 two joined together, about 5-24ths in. in diameter; stem about 

 l-24th in. long and l-48tli in. in diameter. 



Obs. To what size this species might ultimately grow I am 

 ignorant, but that above described appears to be very small. 

 It is, however, amply large enough to show in the section 

 that the tubular vent is the outlet of the tubulated structure., 

 and that, although there is no absolutely cloacal dilatation, 

 this is indicated by the reticulated structure in the centre im- 

 mediately under the vent being more open than towards the 

 circumference. In these two particulars, then, it differs 

 from C. cavata, not more so, perhaps, than in the size and 

 abundance of its spicules, especially on the surface, whereby 

 the thickness of the wall of the tubulation here appears to 

 consist of a plurality of layers instead of one only as in G. 

 cavata. The tubulation is charged internally with ova in 

 the unsegmented state, large, and presenting the germinal 

 vesicle. 



Upon the authority of Hackel I have stated that the 

 " nuclei," mentioned in the two last species, are in his " syn- 



J 



