118 UNIVALVES. 



final addition is made, there is a notch in the last 

 perforation m which the animal places its siphon. 

 When a new hole is opened, one toward 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 disengage 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 vegeta- 

 tion which springs up on the shore. All the 

 shells of this genus are marine, as the name im- 

 plies, being derived from X$ (hals) sea, and UTO, 

 (ota) 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 



* Plate IV. figure 2. 



