20 MULTIVALVES. — LEPAS. 



LEPAS. — Acorn Shell, or Barnacle. 



Animal— a Triton: Shell affixed at the base, and consist- 

 ing of many unequal, erect valves. 



The genus Lepas includes thirty-two species, which, 

 for the most part, bear a strong resemblance to each other, 

 at least with regard to their general formation and out- 

 line. 



The most prominent feature of these shells is their be- 

 ing (with few exceptions) of a more or less conical shape, 

 which is acquired by a number of valves placed perpen- 

 dicularly on a base, broad at the lower margin, and gra- 

 dually tapering towards the summit, which is closed ge- 

 nerally by four smaller valves, placed horizontally, and 

 serving as a lid or covering to the animal within. 



The perpendicular valves are incapable of motion: 

 the horizontal, on the contrary, are moveable at the plea- 

 sure of the animal; which, through their medium, per- 

 forms those functions that are necessary to its existence. 



The Lepas is never found independent or isolated, as 

 most other shells are; on the contrary, all its species are 

 known to attach themselves, in clusters, by their base or 

 fleshy stalk toother bodies, as rocks, coral reefs, and shells; 

 even fish themselves are not exempt from their encroach- 

 ments: the whale, for instance, is frequently found with 

 groups of Lepades adhering to various parts of its body. 

 They also affix themselves to ships, and, though at first 

 invisible, so rapid is their increase in magnitude and num- 

 ber, that the velocity of a vessel is considerably impeded 

 by them. I once observed, on the coast of Africa, a piece 



