10 



PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 69 



Comparison of skulls of Kentriodon pernlx and DelpMnodon dividum Cope — 



Continued 



LATERAL ASPECT 



DelpMnodon dividum True 



Kentriodon pernix 



Zygomatic process slender, about one- 

 third as deep as long, and with 

 anterior extremity obliquely trun- 

 cated. 



Temporal fossa much longer than an- 

 teroposterior diameter of supraor- 

 bital process at orbital border. 



Posterior extremity of maxilla not in 

 contact with transverse crest of su- 

 praoccipital. 



Lambdoid crest apparently undevel- 

 oped, and hence posterior boundary 

 of temporal fossa is uncertain. 



Postorbital projection of supraorbital 

 process long and slender. 



Extremity of rostrum formed by pre- 

 maxiDae and 3 or more of the teeth 

 on each side are lodged in this bone. 



Rostrum at base about two-fifths as 

 deep as wide. 



Zygomatic process robust, about one- 

 half as deep as long, and with anterior 

 extremity squarely truncated. 



Temporal fossa equal to or but slightly 

 longer than anteroposterior diameter 

 of supraorbital process at orbital 

 border. 



Posterior extremity of maxilla in con- 

 tact with transverse crest of supra- 

 occipial. 



Lambdoid crest well developed, form- 

 ing posterior boundary of temporal 

 fossa. 



Postorbital projection of supraorbital 

 process long and slender. 



Extremity of rostrum formed by pre- 

 maxillae and at least 8 of the teeth 

 one each side are lodged in this bone. 



Rostrum at base about two-thirds as 

 deep as wide. 



VEXTBAIi ASPBCT 



DelpMnodon dividum True 



Kentriodon pernix 



Palatines of large size, in contact along 

 midline, and extend forward beyond 

 level of antorbital notches. Each 

 palatine is characterized by a deep 

 anterolateral emargination and large 

 posterior depression. 



Inner margins of maxillae diverge at 

 a point 50 mm. in front of antorbital 

 notches, exposing a broad strip of 

 the vomer for a distance of not more 

 than 90 mm. 



Palatal surface of each maxilla exca- 

 vated at base of rostrum, forming a 

 well-defined concavity. 



Lachrymal large, extending inward be- 

 yond inferior orifice of infraorbital 

 canal, and closely appressed to ante- 

 rior margin of supraorbital process 

 frontal. 



Palatines lodged in elongate depressions 

 in front of respiratory passages and 

 extend forward beyond level of ant- 

 orbital notches. 



Inner margins of maxillae slightly sepa- 

 rated at a point 60 mm. in front of 

 antorbital notches, allowing axial 

 ridge of vomer to appear between 

 them for a distance of not more than 

 40 mm. 



Palatal surface of each maxilla slightly 

 excavated at base of rostrum, but not 

 forming a distinct concavity. 



Lachrymal large, extending inward be- 

 yond inferior orifice of infraorbital 

 canal, and closely appressed to ante- 

 rior margin of supraorbital process of 

 frontal. 



