62 MOLLUSCA. CLEODORA. 



CHAPTER IX. 



Twelfth Class — MoUufica. 



*' As I have observed that you have been very 

 diligent in studying Lamarck since our last les- 

 son," said I\Ir. Elliot, " I propose to make you 

 acquainted with the variations in the univalve 

 genera. 



" The animals of the Mollusca are soft, with- 

 out joints, generally possessing a head, eyes, and 

 tentacula, or feelers. They have also a fleshy 

 membrane, called a foot, which they use for 

 climbing. The orders, excepting the first, are 

 named from the position of this foot. They are 

 five in number. The first order contains very 

 few genera. One genus, named Cleodora, con- 

 tains a species brought from Africa. The shell 

 is curious, transparent, and shaped like the head 

 of a halberd. 



" The animals of the second order, Gaster- 

 opoda, have a muscular foot, or disk, on which 

 they rest. The families are seven. The first, 

 Tritonia, I shall pass over. 



