6 MULTIVALVES_— LEPAS. 
other species possess the intermediate gradations 
of number, as far as twenty-four, which is not un- 
frequent in the L. pollicipes.—The valves, of what- 
ever number they consist, are variously diversified 
with striz, ridges, and grooves. The strive are 
mostly transverse; the ridges, on the contrary, are 
longitudinal, and not uncommonly beset with rough 
projections and acute spines, as in the L. spinosa. 
The valves which compose the operculum, or lid, 
often vary in their number and shape; in some they 
only consist of two; in others, of three or four; and 
sometimes of afar greater number. They are usually 
attached to a ligament, and occasionally present an 
acute form, while in other species they are perfectly 
obtuse. 
The color also differs considerably, though the most 
usual is of a bluish, purplish, or reddish cast; some 
are variegated with black and green, and others are 
greyish-white, as the L. mitella, &c. 
The Lepades are never found detached, but always 
fixed by the base or stalk to other bodies; they adhere in 
clusters to rocks, and often form groups on shells, loose 
stones, anchors, &c.; they are also found on marine ani- 
mals, as the whale andthe turtle. They also affix them- 
selves to ships, and, though at first invisible, so rapid is 
their increase in magnitude and number, that the veloci- 
ty of a vessel is considerably impeded by them. This 
seems to imply that the animal exists in the sea in 
the state of animalcula. 
The interior of some species of this genus is a hollow 
tube, but in others it is divided into separate compart- 
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