MULTIVALVES. LRPAS. 21 



of wood, which had been placed as a buoy, in a few days 

 become covered with a gelatinous substance, and in less 

 than a fortnight was thickly beset with Lepades. Hence 

 it would appear, that the animal exists in the sea in the 

 state of animalcule. 



The exterior of the shell is often varied in form, cover- 

 ing, and coloring} the usual outline is conical j in some, 

 it resembles a pyramid, and in a few is parabolical, or even 

 hemispherical; the Lepas diadema partakes of the latter 

 form, and bears some resemblance to a divided globe. 



The number of valves which constitute the shell is very 

 indefinite; their usual amount is six, but the Lepas pal- 

 mipes has sometimes only four; and other species possess 

 the intermediate gradations of number, as far as twenty- 

 four, which number is sometimes exceeded in the L.,poI- 

 licipes. The valves are variously diversified with striae, 

 ridges, and grooves. 



The ridges are mostly longitudinal; the striae, on the 

 contrary, are transverse, and not unfrequently beset with 

 rough projections and acute spines, as is the case in the 

 J-<epas spinosa. 



The color also differs considerably, though the most 

 usual isof ablueish, purplish, or reddish cast, intermixed 

 with a whitish hue. However, some are marked with 

 black and green alternately, and others are of a greyish- 

 white, or dirty yellow tint, as the L, mitella and others. 



The valves which compose the lid, or operculum, often 

 vary in number and shape; some species have only two, 

 others three or four, and not unfrequently a much greater 

 number. They are usually attached to a ligament, and 

 sometimes present a pointed or acute form, while in other 

 species they are blunt or obtuse. 



The interior of many shells of this genus is a mere va- 



