LEPAS. 27 



favour of a generic distinction ; but, nevertheless, the 

 opinion of Dr. Maton, expressed in the eighth vol. of 

 the Linnaean Transactions, that the gradation from the 

 conic to the compressed species, appears so natural, as 

 not to admit of their being separated without violation 

 of the general principles of the system, must not be 

 disregarded? The Doctor refers to the Lepas mitella, 

 as the link which beautifully unites these two divisions, 

 and adds that " even if a difference in the contained 

 animal should be objected, we cannot agree in that par- 

 ticular being made a ground of distinction, since it is not 

 the exclusive consideration on which Linnaeus professes 

 to found his arrangement." 



The conical shells, or acorns, are found attached to a 

 variety of substances. The common species is frequently 

 abundant on lobsters, oysters, &c. ; and many kinds arrive 

 in England, fixed to the bottom of vessels from foreign 

 countries. Different individuals of the same species, 

 are subject to vary greatly in their external form. 

 This is owing entirely to their manner of growth : the 

 eggs are hardly excluded from the animal, before they 

 become fixed to some neighbouring body; sometimes 

 to the parent shell, or to the support on which that 

 rests, or to rocks, &c. When these eggs are deposited 

 in groups, the shells, as they increase in size, are con- 

 strained for want of room, and they consequently become 

 misshapen and irregular, in proportion as this inconve- 

 nience prevails. This compression so influences their 

 external organization, that the conical tube often loses 

 its natural appearance, and assumes angles that would 

 not otherwise exist. 



The conical shell, although it appears to consist of 

 a single piece, is generally, as has been already observed, 



