30 MULTIVALVES. — LEPAS. 



The colour also differs considerably, though the most usual 

 is of a blueish, pui-plish, 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, &c. 



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 the shells of this genus is either filled up 

 with tubular pores, as in the L. porosa, or divided into 

 separate compartments or chambers, as in the L. quinque- 

 valvis. 



Notwithstanding the great affinity that exists throughout 

 the Lepas tribe, there are a few exceptionable species, in 

 which a resemblance is difficult to be traced; as, for ex- 

 ample, the L. aurita, L. anserifera, L. anatifera, and others 

 in the second division. 



These species are closely allied to each other, but exceed- 

 ingly dissimilar to the rest of their genus ; for the generali- 

 ty of Lepades are affixed to other bodies or substances by 

 the base, or lower part of the shell, whereas these are at- 

 tached by a stalk, stem, or pedicle, which proceeds from 

 the base of the shell to the substance that sustains it. 



The stem by which the shells are supported differs 

 much in quality and substance ; sometimes it appears as a 

 smooth, film-like tube, of a texture finer and thinner than 

 gold-beaters' skin, though somewhat lighter coloured, and 

 ■not unfrequently tinted with bright red or orange; and oc- 

 casionally it is dark or blueish-brown, much coarser, wrink- 

 led, and granulated. 



The L. anserifera and L. anatifera are almost invai'iably 

 composed of five valves; they are supplied with beau- 



