2 74 Bulletin American Museum of Natural History. [Vol. XIII, 



are adapted to flesh and bone cutting by the loss of the talonid 

 exactly as in Felis. We should emphasize the contrast however : 



Carnassiah 

 Oxyanida First upper molar Second lower molar 



Felida Fourth upper premolar First lower molar 



II. Common Creodont Characters of the Oxy/enid^. 



As stated above, many primitive Insectivore-Creodont charac- 

 ters are found in this family which are also found in other types. 

 Among these are : 



An alisphenoid canal ; exposure of mastoid {Fatriofelis) ; small 

 brain ; large temporal fossa ; cranium constricted behind the or- 

 bits (as in Mesonychidae and Arctocyonidse) ; powerful caudals ; 

 elbows everted ; prominent deltoid crest and entepicondylar for- 

 amen of humerus ; separate scapho-lunar ; free centrale ; large 

 trapezium ; small trapezoid ; femur with 3d trochanter and shaft 

 expanded distally; astragalus with flat oblique tibial trochlea and 

 astragalar foramen (as in Creodonta and Pinnipedia) ; small 

 mesocuneiform (functionally analogous to the small trapezoid) ; 

 distal phalanges cleft distally (as in many Creodonts and Con- 

 dylarths) ; metapodials I-V relatively well developed. 



III. Specialized Characters of the Oxy/enid^e. 



Progressive shortening of the face and elongation of cranium 

 with reduction of teeth and development of jaw muscles ; high 

 sagittal crest ; occiput narrow ; a preglenoid process ; a large 

 postmastoid foramen ; no postglenoid foramina ; mandibular 

 condyles scroll-like (as in Felidae) ; atlas with form and verte- 

 brarterial canal as in Felidae (Wortman, '94, p. 137) ; axis with 

 elongate spine ; certain dorsals and lumbars with progressively 

 revolute zygapophyses (as in Mesonychidae and certain Pinnipe- 

 dia, Phoca) ; lumbars with progressively developed anapophyses ; 

 scapula, humerus, and ulna of about equal length ; scapula very 

 large, spreading superiorly (imperfectly known in Oxycena), 

 supra- and infraspinous fossae subequal; powerful acromion and 

 metacromion processes; humerus with exceptionally elongate and 

 prominent deltoid crest, powerful supinator ridge, large entepicon- 



