39 



sponges with the vegetable kingdom. It is also worthy of observation 

 that the normal form of the spicula of sponges is the same, whether 

 they be composed of silex or carbonate of lime, which would still fur- 

 ther seem to indicate that they were truly an animal deposit ; and in- 

 deed Dr. Grant, in a subsequent sentence in the same page of his 

 'Outlines of Comparative Anatomy' that was before quoted, says — 

 " they are formed from materials due to the vital energies of the ani- 

 mals, and they form normal and necessary parts of its structure, like 

 the solid skeletons of higher animals." 



The solidity of the fibre of the sponges of commerce, and of the 

 whole of the keratose species from Australia that I have examined, 

 will render it necessary that Spongia Jistularis should be removed 

 from this groupe, and I therefore beg to suggest the propriety of mak- 

 ing it the type of a new genus to be denominated Fistularia ; and 

 this is the more necessary, as, among the fossil sponges, tubular spe- 

 cies are found in very considerable numbers. 



