40 



CLASS MOLLUSCA. 



The Horx-shaped Planorbis, 

 {Planorbis corneus.) 



The Platiorbis, although differing in form from the 

 Lvmnsea, possesses tb.e same habits, and is found in the 

 same localities. The jelly-like substance which is fre- 

 quently found, in the Spring of the year, attached to 

 water-cresses and other aquatic plants, and which is con- 

 sidered by many to be of a poisonous nature, and looked 

 on as the spawn of toads, is merely the covering of the 

 ova of this and other inhabitants of fresh-water shells ; 

 and, although very disagreeable, certainly not poisonous. 



The Red-mouthed Bulimus, 

 ' {Bulimus hcEmastomus.) 



The Bulimus hcrmastomus is a most beautiful shell ; 

 it is a native of Guiana, and is frequently as much as 

 four inches in length. The most singular part of its 

 natural history is the large size of the egg of the animal 

 in comparison with its magnitude ; it is said to equal 

 that of a moderate-sized pigeon. 



BuUinus hcemastomus. 



Pupa mummia. 



