GENERAL CLASSIFICATION 163 



Pfosmcawrfs [Flat-tailed. H. B.]. 



Uroplates. Lophura. 



Tupinambis. Dracaena. 



BasiUsous. Crocodile [Crooodilia. H.E.]. 



Obdee 4. — Chelonian Reptiles. 

 Double-aurided heart ; body with a carapace and four legs ; jaws 

 without teeth. 

 Chelonia. Emys. 



Chelys. Tortoise. 



SIXTH STAGE OF ORGANISATION. 



Nerves terminating in a spinal cord, and in a brain which fills up 

 the cavity of the cranium ; heart with two ventricles and warm blood. 



{Birds and Mammals.) 



BIRDS. 



(Class XIII. of the Animal Kingdom.) 



Oviparous vertebrate animals with warm blood ; complete respiration 

 by adherent and pierced lungs ; four jointed limbs, two of which are 

 shaped as wings ; feathers on the skin. 



Observations. 



Assuredly birds have a more perfect organisation than reptiles or 

 any other animals of the preceding classes, since they have warm blood, 

 a heart with two ventricles, and their brain fills up the cavity of the 

 cranium, — characters which they have in common only with the most 

 perfect animals composing the final class. 



Yet the birds are clearly only the penultimate step of the animal 

 scale ; for they are less perfect than the mammals, in that they are 

 still oviparous, have no mammae, are destitute of a diaphragm, a 

 bladder, etc., and have fewer faculties. 



In the following table it may be noticed that the first four orders 

 include birds whose young can neither walk nor feed themselves, 

 when they are hatched ; and that the l&st three orders, on the other 

 hand, comprise birds whose young walk and feed themselves as soon as 

 they come out of the egg ; finally, the 7th order, that of the palmipeds 

 seems to me to contain those birds which are most closely related to 

 the first animals of the following class. 



