CUVIER. 519 



for a time at Caen in Normandy. His sojourn on the bor- 

 ders of the sea induced him, already an enthusiast in natural 

 history, to study marine animals, more especially the mol- 

 lusca, and the anatomies of them, which he now made, con- 

 ducted him to the development of his great views on the 

 whole of the animal kingdom. With unwearied zeal he col- 

 lected the materials which were at no distant date to become 

 the basis of a classification which run through all its details 

 in a harmonious parallelism with the development of organi- 

 zation, so that the student of it, when in search of the name 

 and place of the object in his hand, was necessitated simulta- 

 neously to acquire a knowledge of its principal structural 

 peculiarities, on which, again, as Cuvier beautifully ex- 

 plained, all its habits in relation to food, to habitation, and 

 to locomotion were made dependant. The Linnaean system 

 of aver tebra ted animals, even in its primary sections, rested 

 on a single external character. The Insecta were antennu- 

 lated, and the Vermes were tentaculated avertebrates. Had 

 the character been constant or even general, it might have 

 had some claim for adoption, but to a want of constancy was 

 added the fundamental defect of its inappreciable influence 

 over the organisms of the body. Cuvier's object being to 

 give us not merely a key to the name, but to make that key 

 open at the same time a knowledge of the structure and 

 relations of the creature, such arbitrary assumption of a cha- 

 racter was to him useless. After innumerable dissections 

 had made him familiar with many structures, and after a 

 careful consideration of the respective value of characters, as 

 shown in their constancy and influence on the economy of 

 the species, Cuvier resolved to divide the animal kingdom, 

 not as hitherto into two, but into four principal sub-king- 

 doms, drawing their lines of separation from differences ex- 

 hibited in the plan on which their muscular, their nervous, 

 and their circulating systems were formed. " There exist in 

 nature," he says, "four principal forms, or general plans, 

 according to which all animals seem to have been modelled, 

 and the ulterior divisions of which, whatever name the natu- 

 ralist may apply to them, are but comparatively slight mo- 

 Family ii. Mollusks with a single siphon and a foot. Genera Loripes, 



Limnsea. 



Family in. Mollusks with a single siphon. Genera Chimsera, Callitriche. 

 Family iv. Mollusks with a single abdominal siphon and no foot. Genus 



Argus. 



Family v. Mollusks without a siphon but with afoot. Genus Axinea. 

 Family vi. Mollusks without a siphon and without afoot. Genera Daphne, 



Peloris, Echion, Criopus. 



