18-i ON THE FOSSIL BONES OF PACHYDERMATOUS QUADRUPEDS. 



the great depression of the posterior surface, of which we have already 

 sjjoken. 



This superior occipital, the parietal bones A, the frontal bones and 

 upper part of the temporal bones unite very soon to form one single 

 cap, which covers the upper part of the head, e,f, g,l, fig. 3. This 

 junction is established even before the lateral occipitals are united to 

 the superior occipital. I have not seen an interparietal. 



The palatine bone advances as far as the iniddle of the space occu- 

 pied by the molar teeth, a space of which the palatine fissure takes up 

 one-fifth. Immediately behind the molar teeth, the palate bone is as 

 it were enveloped by the pterygoid portion of the sphenoid bone, a, 

 fig. 2, which is turned into a conical surface, so as also to embrace a 

 portion of the maxillary bone ; it thus ascends obliquely forwards, so 

 as to be continued with one ridge of the frontal bone, s'i, which sepa- 

 rates the orbit from the temple : hence it is that the palate bone can 

 be discovered neither in the temple nor in the orbit, and that it re- 

 mains at a very great distance from the lacrymal bone. In the pos»- 

 terior nares, it ascends, as in ordinary cases, but by a very narrow 

 tongue. What appears there of tlie anterior sphenoid, between the 

 two palate bones, is also very small. The point of this portion, in the 

 form of an inverted cone, a, which holds the place of the sphenoidal 

 ala, is occupied by a plate, which remains a considerable time sepa- 

 rated, and which is the internal pterygoid process. The upper part, 

 or the base of this cone, is completed behind, on the internal side of 

 the glenoid surface (facette) by the caisse, which is flat, and situated 

 nearly vertically like the ala itself. The basilar region ascends, as we 

 have already said : the suture which separates the two lateral occipi- 

 tals from the upper, and which continues long visible, is horizontal ; 

 that which separates them from the basilar disappears much sooner. 



A very small portion of the anterior sphenoid, or the orbital ala, is 

 concealed in the orbit, behind the spheno-frontal ridge, is-, of which 

 we have spoken; the foramen opticum, which is small, the spheno- 

 orbital foramen, which includes also the rotundum, and is of considera- 

 ble size, are also concealed in this depression ; there is, at the base of 

 the ala of the sphenoid, a large vidian foramen ; the foramen ovale is 

 confounded with the foramen carotidseum ; that, which is analogous to 

 the spheno-palatine foramen, is in the broad and short sub-orbital 

 canal ; that of the pterygo-palatine is concealed close by the spheno- 

 orbital ; the height of the molar teeth causes this foramen to give rise 

 to a very long canal : the condyloid foramen seems to me to be con- 

 founded with the jugular. 



The section of the head of the elephant {^pl. 10, fig. 5,) is very re- 

 markable by the enormous interval hh c, which separates the two 

 plates of the cranium, before the occipital ridge, and which equals the 

 cerebral cavity c in thickness : by the direction of the canal of the 

 nares, which, far from continuing parallel to the palate, ascends before 

 the entire elevation of the alveoli of the tusks ; by the very great 

 length of the incisive canal ; by the form of the cerebral cavity, which 

 is very convex before, so that the cribriform plate is there placed be- 

 low, as in man. But the posterior portion is as fiat, and even flatter. 



