294 ON THE CLASSES OF THE 



But are we sure that the Crustacea are the most per- 

 fect of Articulated animals ? This is a very different ques- 

 tion from the former, and one to which an affirmative 

 answer may be so strongly maintained, that I enter upon 

 the consideration of it with no small degree of hesitation. 

 The Crustacea, for instance, possess in general four an- 

 tennas, at least six maxillas, a circulation by means of a 

 dorsal ventricle, which distributes the white blood to the 

 branchiae, whence it returns by a ventral canal ; and finally, 

 some few species present vestiges of an ear formed on the 

 plan of some of the lower Vertebrata. But if the number 

 of antennas be any proof of superiority, some Annelides, 

 as the Nereides, have five ; if the number of maxilla? be 

 insisted on, some of the same animals have even nine ; 

 and as to the sense of hearing, before any argument can be 

 founded on this, it must be proved either that insects do 

 not hear, or, if they betray evident tokens of possessing this 

 sense, that their peculiar construction is inferior both in 

 power and complication of design to that of the few 

 Crustacea which display a miserably imperfect trace of 

 the ear of the Vertebrata* Indeed, this subject ought not 

 to be dismissed without remarking that Latreille has never 

 attempted, in any of his late Memoires, to maintain the 

 superiority of the Crustacea, by the circumstance of some 

 of them possessing a part which resembles the vestibulum 

 of a Vertebrated animal. All then that remains to esta- 

 blish their precedence is the system of circulation and re- 

 spiration, which in the Decapoda at least is so similar to 

 that of Amphibia and Fishes. 



It can scarcely have been forgotten that of all the animal 

 functions we have yet had to consider, that of circulation 

 appeared to be the most vague and changeable; nor can 



