216 FOSSIL REPTILES. 



AVhat we have now given respecting the head of the croco- 

 dile, is taken from the ^' Anatomie Comparie'^ of M. Cuvier, 

 and extracted by himself into the '^ Ossemens Fossiles.^^ We 

 shall borrow from the latter work^ to which we must of neces- 

 sity be indebted for all details of this kind, a summary recapitu- 

 lation of the comparison of the bones of the head and face 

 with their analogues. But it will first be necessary to mention 

 the osselet which represents, or rather is substituted for, the 

 four little bones of the ear of mammalia, namely, the malleus, 

 the incus, stapes, and os orbiculare. It consists of a small, long, 

 narrow, elliptical plate, applied over the upper fenestra, and 

 from which proceeds a sort of handle, long and slender, and 

 which is fixed to the membrana tympani. There it is curved, 

 and assumes a cartilaginous consistence. From the hinder 

 paries of the long cavity proceeds a muscular filament, which is 

 attached to the handle of the bone, at about a third of its 

 length, and a doubling of the internal tunic of the tympanum 

 forms a triangular ligament which extends to the same point, 

 and thus contributes to fix this handle to its recurved and tym- 

 panic part. — Now to the recapitulation. 



The intermaxillary, maxillary, nasal, lachrymal, jugal, and 

 palatine bones, belong to the head of the crocodile equally with 

 the mammalia, occupy the same positions, and fulfil the same 

 offices. 



The ethmoid is similarly formed, of a sieve-like plate, lateral 

 wings, upper cornets, and a vertical plate; but it remains, for 

 the most part, cartilaginous. Two pieces seem to represent 

 the lower portion of its vertical plate or vomer ^ two others some 

 portion of its upper anfractuosities. 



The frontal bone in its position and functions is the same as 

 in the mammalia, but its ante and post-orbital apophyses are 

 distinct bones. 



The same is the case with the occipital, and it remains 

 divided into four portions, as in the mammiferous foetus. 



The same may be said of the body of the sphenoid, but it is 



