H AM OTIS. 105 



these, which have no generic deficiency but that of 

 the foraminal ducts. 



Did the animals inhabiting the shells of one 

 section differ from that which constructs the 

 other, it would not prevent a generic union of 

 them, according to our system ; but no such fact 

 of their dissimilarity is ascertained. Some of the 

 identical species open, and make use of a different 

 number of their siphons. Why may not then a 

 Limax be permitted to choose a water-tight re- 

 ceptacle, though his fellows prefer one that is 

 pervious to the winds and waves ? 



The Haliotis, from d\g, the sea, and wra, ears, is 

 thus denominated on account of its ear-like form. 

 The animal is attached by so adhesive a property 

 to the surface of the rocks, that it requires the ut- 

 most force to disengage it, though by a spontaneous 

 action it is able to remove with facility from place 

 to place. It is probable that in some individuals 

 of this family, as in some of Helix and Patella, the 

 shell does not cover the whole body of the Mol- 

 luscous worm, but merely the vital organs. 



