58 L E P A S. 



tremely dissimilar, are yet congeners in their prin- 

 cipal essential characters, being multivalve, and 

 parasitical ; and the species pass gradually from 

 one conformation to the other in so connected a 

 series, that it would seem needless, and indeed de- 

 structive of simplicity and order, to separate or 

 disarrange them. The aperture in the conical di- 

 vision increases proportionably to the growth of the 

 shell, by means of the extension, in width, of the 

 triangular parts between the valves. The pedun- 

 cled species are called Barnacles, from a strange 

 prejudice formerly entertained, that they were 

 transformed into geese ; originating perhaps in 

 their feathery tentacula, and in their being observ- 

 ed moving about on their long flexible tubes above 

 the surface of the water. Both divisions are in- 

 variably attached to extraneous substances, usually 

 in groups. The genus takes its name from Xstt^).;. 

 the rocky to which the shells adhere. 



