246 THE ANATOMY OF VERTEBRATED ANIMALS. 



a gi'eat parietal foramen close to the coronal suture, but 

 are completely divided by a median fissure. Ossified pre- 

 sphenoids and orbitosphenoids appear to liave been alto- 

 gether absent, and the frontal bones are relatively small. 

 The pro-otic bones are, as usual, situated in front of the 

 ex-occipitals ; and between the latter and them there may 

 sometimes be discerned a conical bone with a broad base, 

 which appears to be fitted in between the ex-occipital and 

 the pro-otic. If this bone were not so large, it might well 

 be regarded as a stapes, but it is possible that, as Cuvier 

 suggests, it answers to the separate opisthotic of the 

 Chelonia. 



In the naso-premaxillary segment, the nasal bones, con- 

 tinuing the direction of the frontals, attain considerable 

 size, but the premaxillse make up by far the greater part 

 of the snout. The maxillae are reduced, as in bii'ds, to 

 comparatively small and slender rodlike bones, bounding 

 only a fraction of the gape. The vomers are elongated, 

 and situated in the middle line on the underside of the 

 snout. 



The nostrils are small apertures close to the orbits, 

 Ijounded by the nasal, lachi-ymal, and premaxiUary bones. 



On each side of the frontal there is a large prefrontal, 

 which passes back above to meet the postfrontal, and thus 

 bound the orbit. Below, the maxilla is connected with a 

 jugal. From the postfrontal to the jugal, the posterior 

 margin of the orbit is constituted by a distinct, curved, 

 postorbital bone (Fig. 76, A, Pt.O). A broad and flat 

 quadi'ato-jugal {Q.j.) passes from the end of the jugal to 

 the lower end of the quadrate, and covers in the lower 

 and posterior pai-t of the infra-temporal fossa. The space 

 between this bone, the postorbital, the postfrontal, and 

 the squamosal is occupied by another flattened bone (Fig. 

 76, A, St.), which Cuvier calls the temporal, biit which 

 does not appear to have any precise homologue among 

 other Reptilia. The squamosal bone is very large and 

 stout, and forms the postero-external angle of the skull. 

 From this point it sends a process forwards to meet the 



