148 CLASS IlI.—ORDER I. 



tracted from its ashes, which even sometimes ex- 

 ceeds half the weight of the dried Polypidom. 



They differ from the marine Spongia by their fresh- 

 water habitation, and by their disagreeable smell 

 when first taken from the water. 



These singular beings are yet but little known ; no 

 exotics are to be found among the collections. It is 

 however probable that the fountains, rivulets, and 

 rivers of other regions contain them as well as our 

 own ; but they have not been suiSiciently attractive 

 hitherto to catch the attention of voyagers, occupied 

 in more important objects, or engaged by forms more 

 elegant, or colours of greater brilliancy. 



The Ephydatias are seldom of the same form ; 

 their colour is green, of different shades, apparently va- 

 rying with the nature of the body to which they adhere. 



They inhabit fresh and limpid waters, covering 

 stones, roots, and almost every substance that comes 

 within their reach ; frequently acquiring considerable 

 size. 



CANAL. 



1. Ephydatia canalium. Branching and dicho- 

 tomous ; branches round and bent. 



In an aqueduct. 



fLUVIATIC. 



2. 'Efhydati \ JIuviatilis. Upright, fragile, and of 

 no particular form. 



In ponds. • 



FRIABLE. 



3. Ephydatia friahilis. Ashy, friable, sessile, 

 without form, and a little branching. 



In a lake near Buda. 



