44 ORDER CHENOMORPHM 



convex at one end and concave at the other end of the vertebra) ; (2) in the bifur- 

 cation of the nasals, they are holorhinal (i.e., the nasal opening is rounded poste- 

 riorly instead of being continued as a narrow slit on to the frontal part of the 

 skull); (3) the sternum has but one xiphoid process on each side of the median 

 process; (4) the basipterygoid processes of the basisphenoid bone articulate with the 

 pterygoids far forward and as close to the palatines as possible; (5) the lateral oc- 

 cipital vacuities may or may not be present; (6) the angle of the mandible is much 

 produced behind the articulation and recurved. The maxillo-palatines are thin 

 plates fused with each other across the palate for their entire length (i.e., the skull 

 is desmognathous). The combination of the third and fourth characters is diagnostic 

 of the suborder, and within the suborder the combination of the second, fourth, and 

 sixth is equally so. 



OS 



