OVIPARA. 215 
OF THE OVIPAROUS VERTEBRATA. 
Although the three classes of the Oviparous Vertebrata 
differ greatly from each other in their quantum of respiration, 
and in all that relates to it, viz. the power of motion and the 
energy of the senses, they present several common characters 
when opposed to the Mammalia, or Viviparous Vertebrata. 
The hemispheres of their brain are very slender, and are 
not united by a ‘corpus callosum; the crura of the cerebellum 
do not form that protuberance called the pons Varolit; the 
nates—at least in two of these classes—become greatly de- 
veloped, contain a ventricle, and are not covered by the hemi- 
spheres, but are visible below, or on the sides of the cere- 
brum; their nostrils are less complex; the ear has not so 
many small bones, which in several are totally wanting; the 
cochlea, when it exists, which is only the case in Birds, is 
much more simple, &c. Their lower jaw, always composed 
of numerous pieces, is attached by a concave facet to a salient 
process, which belongs to the temporal bone, but separated 
from its petrous portion; the bones of their cranium are more 
_ subdivided, although they occupy the same relative places, 
and fulfil similar functions; thus the os frontis is composed 
of five or six pieces, &c. ‘The orbits are merely separated 
by an osseous lamina of the sphenoidal bone, or by a membrane. 
When these animals have anterior extremities, besides the 
clavicle, which is frequently united to its fellow on the oppo- 
site side, and is then called fourchette, the scapula also rests 
upon the sternum, by a very broad and long coracoid apophy- 
‘sis. The larynx is more simple, and has no epiglottis; the 
lungs are not separated from the abdomen by a perfect dia- 
phragm, &c. To render all these affinities sensible, however, 
it would be necessary to enter into anatomical details, which 
