6 Mr. H. J. Carter on the " Collar " 



but its three other rays bind down the rest of the spicular 

 structure on the surface at the same time (PI. I. fig. 6, c). It 

 is therefore as much a surface- as a cloacal spicule ; while, in 

 all the other calcareous sponges that I have seen, it (that is, 

 the quadriradiate) is almost entirely confined to the cloacal 

 surface. The two other quadriradiate spicules are also chiefly 

 confined to the inner surface of the cloaca here as well as in 

 Leuconia nivea^ where, with the minute spinous spicule, they 

 also chiefly form the lining of the excretory canals ; but the 

 great spur of the great quadriradiate spicule of Leuconia 

 Johnstonii is, of course, absent. 



Confirmation ofProf. James-Clark's Discovery of the " Collar'''' 

 round the Cilium of the Sponge-cell. 



In the October Number of the ^ Annals ' for last year my 

 paper on the " Ultimate Structure of the Marine Sponges " 

 was published (vol. vi. p. 329), at the end of which (p. 341) 

 are the following paragraphs : — 



" I have only now to add a word or two, in conclusion, on 

 the real nature of the animal of the Sponges abstractedly. 



" The only naturalist, to my knowledge, who has turned 

 his attention directly to this all-important point connected 

 with them is Prof. H. James-Clark, of Boston, to whose va- 

 luable memoir on the subject, entitled, " Spongiae ciliatse or 

 Infusoria flagellata " (Mem. Bost. Soc. Nat. Hist. vol. i. pt. 3, 

 pis. 9 & 10, read June 20, 1866 ; reprinted in the ' Annals,' 

 vol. i. p. 133, Feb. 1868) I have alluded at the commencement 

 of this paper. 



" The object of Prof. James-Clark is to prove that the 

 monociliated sponge-cell is a distinct flagellated infusorium, 

 possessing an oral and an anal orifice respectively, in close 

 approximation, at the bottom of a funnel-shaped retractile ex- 

 pansion which surrounds the base of the cilium, and also a 

 nucleus and two contracting vesicles ; fm-ther, that this flagel- 

 lated infusorium is in no sense whatever related to the Rhizo- 

 poda ; and that it is an aggregation or colony of such Infusoria 

 which produces the ' true ciliated Siwngioe.'' 



" I cannot altogether endorse Prof. James-Clark's views, as 

 I have stated (Annals, Sept. 1869, vol. iv. p. 196), nor do I 

 desire to dispute his conclusions here." 



It is with great pleasure that I can now endorse them — that 

 is, that I am now able to confirm all that Prof. James-Clark 

 has stated of the flagellated sponge-cell in the valuable memoir 

 to which I have referred. 



For two months past Grantia comjpressa has been growing 



