FOSSIL REPTILES. 253 



the frontal anterior bone, which takes its usual place in the 

 frame work of the orbit, is also articulated as usual to the 

 ante-orbital apophysis of the maxillary, forms the anterior par- 

 tition which separates the orbit from the nose, and articulates 

 below with the palatine and the vomer, leaving between itself, 

 the maxillary, and the palatine, an oblong foramen, which 

 opens into the back-nostrils. 



The osseous cavity of the nose is oblong, and formed by the 

 maxillaries, the inter-maxillaries, the vomer, the two anterior, 

 and the principal frontals. The extent of the frontals, and the 

 absence of nasal bones, cause the first to articulate one with 

 the other, and to extend above the orbit, and outside the prin- 

 cipal frontals, as far as the posterior frontals in this species, 

 and very near them in some others. 



The inter-maxillaries have no ascending apophysis. They 

 form, as usual, the end of the muzzle, and go back into the 

 palate between the maxillaries, and even between the back- 

 nostrils, as far as the vomer. These back-nostrils are two 

 wide apertures, pierced on each side, in the midst of the floor 

 of the nasal cavity, between the maxillaries, the inter-maxil- 

 laries, the vomer, and the anterior frontals. 



The bottom of the cavity of the nose is covered above, and 

 closed behind by the principal frontals, which leave between 

 them a wide aperture, closed in the fresh subject by a cartilage, 

 which allows the threads of the olfactory nerve to pass. 



Lower down, and laterally, there is between the frontal, the 

 anterior frontal, and the vomer, a tolerably large space, closed 

 in the fresh subject by a continuation of the same cartilage 

 which represents the os planum. 



In the land-tortoise there is nothing, or scarcely anything, of 

 a simple, inter-orbital, cartilaginous partition, which want results 

 from the great depth of the nasal cavities behind, and from the 

 anterior and cartilaginous portion of the cerebral box approach- 

 ing them considerably. But this is not the case with other 

 sub-genera. 



