194 Mr. H. J. Carter on Grayella cyatliopliora, 



seem too minute for this. In short, there are many more 

 apertures than there are cup-like bodies ; so we have to ac- 

 count for the superfluity. 



It is evident that Prof. Huxley's hypothetical diagram 

 (Introduct. to the Classification of Animals, p. 15, fig. 4), by 

 which a globular cavity lined with ciliated sponge-cells is 

 made to have two apertures (viz. one receiving a stream of 

 water directly from the exterior, and the other ti-ansmitting it 

 into the excretory canal), will not apply to Grayella cyatho- 

 phora. We must have another hypothesis here, more espe- 

 cially for the canals which do not communicate with a cup- 

 like body. 



Certainly, in the young SjyongiUa, growing from the seed- 

 like body, the particles of food (carmine) may be seen to 

 pass into the general chamber surrounding the parenchyma, 

 and thence into ampuUaceous sacs imbedded in the latter. 

 That these sacs are lined with monociliated and unciliated 

 sponge-cells which incept the particles, apparently transmitted 

 through a single aperture in this sac, is also evident. But I 

 could never see how the undigested portions got into the ex- 

 cretory canals. I had therefore to conceive that it took place 

 through the bodies of the sponge-cells themselves, as a particle 

 might be incepted on one side of an Amoeba and ejected at the 

 other — in short, that the sponge-cells of the ampullaceous sac 

 acted as a kind of partition between the chamber receiving the 

 particles and the canals carrying off the refuse. (See my figures 

 and descriptions of the ultimate structm'e of Sjpongilla^ Annals, 

 ser. 2. vol. xx. p. 21.) 



But, be this as it may with Spongilla^ it is with Grayella 

 cyatlio2)hora that we are now chiefly concerned ; and here, 

 although it is plain that there is a direct communication be- 

 tween the cup-like body and the excretory canal, it is equally 

 plain also that this is chiefly for aeration and for the admis- 

 sion of nutritive particles to some other organs. 



We have therefore to look for these organs ; and falling back 

 upon the canals which do not come directly from the cup-like 

 bodies, and certain cavernous excavations in the parenchyma 

 above mentioned, which appear to be dilatations of the excre- 

 tory canals along their course, analogous to, if not homologous 

 with, the areolar cavities in Pachymatisma Johnstonia (Annals, 

 this volume, pp. 12 & 13), it does not seem improbable that 

 the sponge-cells which incept the particles may be here 

 situated. 



But whether they are in vesicular dilatations (like the " am- 

 pullaceous sac ") at the ends of these canals, or Avhether in 

 globular dilatations like those in Prof. Huxley's hypothetical 



