MULTIVALVES——LEPAS. 5 
LEPAS.—Acorn SHELL or BARNACLE. 
DESCRIPTION OF PLATE II. 
Div. I. —Fam. 1. Fig. 1. L. Tintinnabulum.—4. L. Clavata.—5. L. Verruca. 
Fam. 2. Fig. 3. L. Quinquevalvis. 
Fam. 3. Fig. 2. L. Purpurascens. 
Dw. Il.—Fam. 1. Fig. 6. L. Mitella.—8. L. Pollicipes. 
Fam.2. Fig. 7. L. Anatifera. 
Shell affixed at the base, and consisting of many wnequal erect valves. 
OF the genus Lepas forty-three species are known, 
and they are in general so well characterized that 
they cannot be confounded with those of any other 
genus. 
The exterior of the shell is often varied in shape, 
covering, and coloring; the usual outline is conical, 
but in some instances, hemispherical; which form is 
acquired by a number of valves being placed perpen- 
dicularly on a base, broad at the lower margin, and 
gradually tapering towards the summit, which is clos- 
ed by other smaller valves, placed nearly horizontally, 
thereby serving as a lid or covering to the animal 
within. The perpendicular valves are incapable 
of motion; the horizontal, on the contrary, are move- 
able at the will of the animal; which through their 
medium, performs those functions that are neces- 
sary to its existence. 
The number of valves which constitute the shell 
is often very indefinite, their usual amount is six; 
but the L. palmipes has sometimes only four; and 
