14 Mr. H. J. Carter on the Suhspherous Sponges. 



glass cavity and its diaphragm remain the same in all other 

 respects. 



This dermal sarcode presents a great number of minute 

 papillae scattered more or less over its whole surface, each of 

 which is terminated by an equally minute aperture, the latter 

 frequently more in appearance than reality, since a thin film 

 of sarcode is frequently stretched across it, which, in its turn, 

 may or may not be provided with a central opening, the pre- 

 sence or absence of these openings being probably fortuitous — 

 that is, depending on certain conditions of the sarcode during 

 the death or desiccation of the sponge. (PI. II. fig. 10.) 



The papillary apertures, averaging a little more or less 

 than 1-lOOOth of an inch in diameter, are chiefly congregated, 

 over the openings of the hourglass-shaped cavities of the crust, 

 into distinct areas, each of which is more or less convex and 

 presents an appearance like the top of a pepper-box (that is to 

 say, a convexity pierced by the papillary apertures), which area 

 itself is often pursed outwards in the centre also in a papillary 

 form, with an aperture, in the living state, probably, at its 

 termination. 



Lastly, the papillary apertures which are immediately over 

 the outer part of the hourglass-shaped opening in the crust 

 lead directly into this cavity, and those at the circumference 

 of the area to minute canals which pass down to the vault of 

 the areolar cavity (into which the inner portion of the hour- 

 glass-shaped opening expands itself), through the hourglass 

 opening, but outside its sarcodal lining ; while the papillary 

 apertures of the crust generally (that is, those altogether outside 

 the areaj) lead to similar canals which traverse the crust oppo- 

 site to them, and also open within into the vault of the nearest 

 areolar cavity. The two latter sets are the openings of the 

 canals to which I have alluded when describing the inner 

 portion of the hourglass-shaped opening in the crust. 



I have not been able to observe any a23ertures opening into 

 either portion of the hourglass cavity through its sarcodal 

 lining direct ; and the minute spicules so abundant in the 

 dermal sarcode are seldom present in it or in its diaphragmatic 

 expansion. These spicules in the dermal sarcode are fre- 

 quently arranged sponge-like around the papillary apertures — 

 that is to say, after the manner of poles supporting a conical 

 tent. 



Thus it will be seen that there are many points of difference 

 between Dr. Bowerbank's and my descriptions, which need 

 not be particularized, as both the latter are given above, in 

 extenso • and should ocular demonstration be desired to confirm 

 the statements I have made, this may be obtained by vertical 



