302 ON THE CLASSES OF THE 



esprit sage et toujours prei a revenir sur ses pas, lorsgu'il 

 reconnaitra son erreur. Entre le poisson dont T organiza- 

 tion est la plus simple et le crustace le plus parfait sous ce 

 rapport, il existe, aifisi queje I'ai dit dans mon memoire, 

 un hiatus quil nous est maintenant impossible de remplir. 

 Quand bien mtme on admeitrait avec moi que les lamproies 

 et les gastrobranches sont les dernier s de la classe despoissons, 

 la forme et la situation de leur colomie vertebrate ne pour- 

 raient pas etre comparees avec la mo'elle epiniere des Crus- 

 taces" 



But if we agree with MM. Cuvier and Lamarck that the 

 Annelides come nearer to the Vertebrated animals than to 

 the Crustacea or indeed any Annulosa, it may still be asked, 

 how we would account for the singular circumstance of 

 the Crustacea possessing a system of circulation and bran- 

 chiae resembling those of a Vertebrated animal. Now 

 M. Latreille has given me the answer to tliis question 

 himself, by bringing these animals into comparison with 

 the Amphibia, and by assimilating the Arachnida to 

 some of the Reptilia, — both analogies, I confess, wmch 

 I should never of myself have thought of; but the 

 statement of them by so great a naturalist has served to 

 convince me that what in reality is only a relation of ana- 

 logy has been mistaken for a relation of affinity. This is 

 so common a cause of delusion in the investigation of na- 

 tural affinities, that T shall be obliged to return to a fuller 

 consideration of it in the following chapter, where the 

 mischief it has occasioned will be more perceptible; 

 and in the mean time shall only observe that the Crustacea 

 possess a system of circulation and respiration analogous 

 to that of the Amphibia; that Uke these they are fond of 

 water, but can subsist for some time out of it; that som^ 



