ESSAY ON SPONGES. 



Having advanced an opinion upon the consti^ 

 tution of sponge, it must be observed, that I have 

 not enumerated what has been usually considered i 

 as fresh- water species of this genus, in my cata- 5 

 logue of British sponges, conceiving that they are 

 actually of a different nature. Lamarck has se- 

 parated these from Spongia, and has placed them ^ 

 in a new genus denominated Cristatella, which ' 

 bears evident polypes. Bosc, however, conceives ) 

 Lamarck has been deceived by a figure in Roesel; j 

 as he declares that he has examined a vast quanti- \ 

 ty of what is called Spongia fluviatilis, and never 

 could discover animal organization with signs of 

 lifb. ' 



Not having had an opportunity of examining 

 recent specimens of these fresh-water species of ■ 

 supposed sponges, I must confess that, by the 

 structure alone in an 07id state, I am led to an 

 opinion that they do not truly belong to the genus 

 Spongia \ 



* This fibrous brittle substance is evidently of animal origin/ 

 by its odour in combustion : the numerous minute globules it 

 contains of the same figure and size, interspersed throughout 

 the whole substance, have evident characters of ova connected 

 together by glutinous filaments, which form the reticulated mass. 

 If these minute globes were cells of polypes, or any other perfect 

 animal, they would possess an aperture ; whereas they have no 

 opening. They are strong, tough, and polished within, like 

 what the remains of a glareous matter would be when dried in 



