14 Mr. H. J. Carter on the Polype-like 



Although it is easy to determine the form of the groups of 

 sponge-cells in 8pongilla, it is not so easy to see by what 

 channels the particles of colouring-matter are immediately 

 taken into them^ or to see how they or the ingesta get from the 

 cells into the excretory canals ; for the cilia of the sponge- 

 cells are in the interior of the ampullaceous sac, where they 

 may be seen vibrating through the transparent circular area 

 (aperture?). In my latest observations it seemed to me that 

 the particles got into the sponge-cells of the ampullaceous sac 

 through several different channels and holes, perhaps, in the 

 latter, and that the discharged portions passed into the excre- 

 tory canals through the transparent aperture ; but of this I am 

 not certain, and must now leave others to determine it. 



The same kind of ampullaceous sac may be seen in many 

 of the marine siliceous sponges, of which perhaps Isodictya 

 simulans affords the best example. It has been figured by 

 Schmidt under the name of " Wimperkorb " from Reniera 

 aqueductus &c. (Suppl. Spong. Adriat. 1864, p. 13, t. l.fig. 17); 

 but this author does not allude to my description and figure 

 of it in the ^Annals ' for 1857, although the feeding of Spon- 

 gilla with carmine by Lieberkiihn and myself is noticed. 



Thus the peculiar grouping of the sponge-cells in Spongilla 

 and many of the marine sponges has been ascertained. 



But in the Calcispongige they seem to cover the whole 

 surface of the sarcode which lines the areolar cavities of 

 the parenchyma (PI. I. fig. 8, and PI. II. fig. 29), with the 

 exception, of course, of their incurrent and excurrent aper- 

 tures, the latter of which, where there is no system of excur- 

 rent canals, finally open by large orifices directly into the 

 cloaca. 



So far as structure goes, Grantia ciliata does not differ, 

 in the form of its areolar cavities and the absence of the ex- 

 cretory canal-system, from Cliona celata^ in which, as my 

 figure seems to show, the sponge-ceUs are still grouped in a 

 spherical form (PI. II. fig. 38). 



It therefore remains for future observation to determine how 

 the sponge-cells are grouped, generally and respectively, both 

 in the siliceous and calcareous sponges. 



Cliona corallinoides (Hancock in Ann. Nat. Hist. April 1867, 

 vol. xix. p. 238, pi. 7. fig. 3). PI. II. figs. 33-37. 



Next to the sponge-cells, perhaps the most interesting organ 

 is the dermal sarcode ; for this, as I have before shown (Ult. 

 Struct, of Spongilla) literally commands the openings on the 

 surface. It can either extemporize them in any part, or close 



