CLASSIFICATION, AND PHYLOGENY OF THE DIJsOENITHID^. 421 



Mandible slenderer than in any other genus, moderately deflected ; posterior angular 

 process well developed. 



Genus Anomalopteryx. 



Occipital plane distinctly inclined backwards, the condyle being hidden in a view 



from above by the supraforaminal ridge and also in a view from the side by the 



paroccipital process. 

 Occipital crest slight, but whole median supraoccipital region dilated to form a wide 



transversely convex ridge. 

 Width at paroccipital process about one and three quarters length of basis cranii. 

 Anterior and posterior lambdoidal ridges usually widely separated. 

 Width at squamosals about double length of basis cranii. 

 Mamillar tuberosities large. 

 Margin of tympanic cavity sharply angled. 

 Temporal fossa very large ; distance between temporal ridges about half width of 



cranium at temporal fossae ; width of temporal fossa more than three fourths 



length of basis cranii. 

 Posterior limb of temporal ridge confluent with lambdoidal ridge ; mid-temporal 



ridge well marked and often prominent. 

 Posterior temporal fossa wide ; inferior temporal ridge strong ; no pretympanic 



process. 

 Zygomatic process short and blunt. 



Margin of orbit obtusely angled ; postorbital process evenly curved. 

 Distance between optic foramina less than one third length of basis cranii. 

 Presphenoid fossa unusually well defined. 



Antorbital very thin ; a large supraorbital fenestra ; no definite postchoanal bar. 

 Lateral contour of premaxiila much straighter than in any other genus ; body narrow 



and pointed, its width about two thirds of its length and three fourths of length 



of basis cranii ; a distinct prenarial septum. 

 Maxillo-jugal arch stout and nearly straight. 

 Orbital process of quadrate long, compressed, and rather pointed at the tip ; a large 



pneumatic foramen on the mesial surface of the otic process and often a second 



foramen on its posterior surface. 

 Mandible stout and nearly straight; symphysis narrow, with a moderately 



prominent ventral ridge ; posterior angular process strong. 



VOL. xjii. — PAET XI. No. 7. — October, 1895. 



