» CLASS AVES. 



crura cerebelU do not form that protuberance called 

 the pom Varolii; their nostrils are less complicated ; 

 their ears have by no means so many little bones, and 

 in many species have, indeed, none ; the cochlea, 

 when it exists, is much more simple, &c. The lower 

 jaw, composed always of several pieces, is attached 

 by a concave facet to a saliant portion of the tempo- 

 ral bone, but which is separated from the petrous por- 

 tion. The bones of the cranium are more subdivided, 

 or continue so longer, although they occupy the same 

 relative places, and fulfil the same functions ; thus the 

 frontal has five or six pieces, &c. The orbits are se- 

 parated from the sphenoid only by a laminous bone. 

 When these animals have anterior extremities besides 

 the clavicle, which is often united with that of the 

 opposite side, and takes the name of the os fur- 

 catum, or merry-thought, the omoplate is supported 

 moreover on the sternum by a very long and large 

 coracoid apophysis. The larynx is more simple, and 

 is without an epiglottis ; the lungs are not separated 

 from the abdomen by a complete diaphragm, &c. 

 But, to speak of all these points, it would be neces- 

 sary to enter into more anatomical details than can 

 here be afforded. Suffice it, therefore, to have re- 

 marked the general analogy of the ovipara among 

 themselves, greater, with reference to the plan on 

 which they are constructed, than that of any of them 

 with the mammalia. 



Oviparous generation consists essentially in this, — 

 that the young is not fixed by a placentum to the ute- 

 rus, or oviduct, but remains separated by the most 



