ORDER CHELONIA. 23 



to viviparous quadrupeds, which may be considered as the 

 elite of the animal kingdom, notwithstanding that the majo- 

 rity of reptiles have four feet. It is rather Avith birds and 

 fishes that they seem to exhibit an alliance of manners and 

 habits. There is an inter-resemblance in these classes in 

 many points of internal organization, and even in the exter- 

 nal forms of some species ; but it is more especially striking 

 in the reptiles and the fish. 



Vertebrated animals, with cold blood, may, in fact, be 

 considered as almost forming another world. They preserve 

 some analogy, it is true, with the superior classes, in the 

 bony skeleton, in the general arrangement of the brain, of 

 the senses, and of the principal viscera ; but the heart, both 

 in reptiles and fishes, has but one -ventricle, or cavity. The 

 vesicular lungs of the reptiles, instead of receiving, as in 

 mammifera and birds, the entire blood to be impregnated 

 with the vital air, receives but a small streamlet of the venous 

 blood, which is even oxygenated but feebly, for these ani- 

 mals breathe but very slowly through this pulmonary viscus, 

 the tissue of which is so very lax. From this it results, that 

 tlie blood, scarcely warmed and vivified by combination with 

 the vital air, excites but languidly the entire organization ; 

 accordingly, we find the reptiles nearly cold to the touch like 

 inanimate bodies : for this reason, they are observed to seek 

 and court atmospheric heat, or the warm sunshine ; and the 

 cold of winter reduces them to a state of torpidity. Tliey 

 seem, for the most part, to vegetate rather than live, to be 

 insensible of a wound, and even scarcely to discover any con- 

 siderable degree of anguish when cut in pieces. Their organi- 

 zation very speedily renews many parts, sucli as the tail or 

 toes, when they have been removed. As these animals have 

 but very little cerebellum in proportion to their size, and a 

 brain composed of but six small tubercles, their existence is 

 not so absolutely concentrated in their head as ours. It 



