118 UNIVALVES. 



addition is made, there is a notch in the last per- 

 foration in which the animal places its siphon. 

 When a new hole is opened, one towards the spire 

 is closed, and there are seldom more than seven 

 or eight unstopped at the same time. When the 

 Haliotides traverse the rocks, their shell is like a 

 reversed basin, and the circumference is bordered 

 by the foot of the animal, which is very large ; 

 the spire is at the posterior part as it advances. 

 In their repose they adhere to the rocks with such 

 tenacity that it requires the utmost force to dis- 

 engage them, though they can with the greatest 

 facility remove themselves. They are always 

 found near the surface of the water, and in serene 

 summer nights they feed on the vegetation which 

 springs up on the shore. All the shells of this 

 genus are marine, as the name implies, being 

 derived from a A; (hals) sea, and Jra (of a) ears. 

 Most of the species inhabit the seas of warm 

 climates. They have no operculum. 



HALIOTIS Tuberculata* 



COMMON SEA-EAR. 



Specific Character. Shell strong, thick, sub- 

 ovate, transversely wrinkled, striated longitudi- 

 nally, and tuberculated ; near the inner margin is 

 a ridge extending the length of the shell, and ter- 



* Plate IV. figure 2. 



