round the Cilium of the Sponge-cell. 9 



larly ; but, before doing so, I would premise that Prof. James- 

 Clark's memoir, although headed "Spongise ciliatse &e.," is 

 chiefly on flagellated Infusoria — four new genera of which, viz. 

 Btcosoeca, Codonoeca, Codosiga, and Saljjingoeca, including six 

 species, partly freshwater and partly marine, growing separately 

 or in groups on stalks, and all possessing the " collar " charac- 

 terizing the sponge-cell, he has described and illustrated in 

 detail, before that of Leucosolenia hotryoides. Hence he not 

 only gives the sponge-cell, but several other minute monocil- 

 iated and collared monadine organisms almost identical with 

 it, which live respectively in the sea and in fresh water — 

 whereby his observations on the form and habits of the sponge- 

 cell are confirmed by totally independent evidence. 



I do not know that any one has published an account of the 

 same kind of monadine infusoria ; but now that I am aware of 

 what they are, and have seen them in the sponge, I remember 

 to have frequently seen such organisms as are represented by 

 Prof. James-Clark under the name of 8alpingoeca amphoridmm 

 (figs. 37, a-d^ pi. 9, I. c.) on the filaments of Spirogyra or 

 Cladophora at Bombay, and have them figured in several 

 parts of my journal, beginning as far back as " April 15th, 

 1855 " (PI. II. fig. 42) ; but at that time my microscopic 

 power was too low to see them properly, and therefore, as 

 often as I met with them, they were so far disregarded. 

 Hence it is probable that when Prof. James-Clark's discove- 

 ries become better known (which, like all valuable communi- 

 cations of the kind, may be too far in advance to be recognized 

 in the lifetime of the author) these Infusoria may be often no- 

 ticed ; indeed I hardly despair now of seeing some of them 

 one day myself, especially the freshwater Codosiga pulcher- 

 rima, which can be " readily recognized under as low a mag- 

 nify ing~power as two hundred diameters " (Z. c. p. 10). 



Returning, then, to Grantia compressa^ so far as the sponge- 

 cell alone goes, it is the same as that of Leucosolenia hotryoides^ 

 viz. globular in form, composed of a plastic exterior, en- 

 closing granuliferous mucus or protoplasm, a nucleus and 

 conti-acting vesicles, besides, perhaps, other organs at present 

 unknown (PI. I. fig. 13, a), having at one part a non-granular 

 portion, which is extensible (5). This part, which we will 

 call the " rostrum," is polymorphic and protrusible, as in Bif- 

 fiugia, and frequently assumes different shapes, but especially 

 a cylindrical one rounded at the free end, from the summit of 

 which convexity the cilium [d) proceeds, and from around its 

 base a funnel-shaped delicate film like a fringe or frill, which, 

 with Prof. James-Clark, we shall call the " collar " (c). 



Although the rostrum is not represented in Prof. James- 



