Cope.] 1«W [Dec. 16, 



The Anaptomorphus homunculus was nocturnal in its habits, and its food 

 was like that of the smaller lemurs of Madagascar and the Malaysian 

 islands. Its size is a little less than that of the Tarsius spectrum. The 

 typical specimen was found by Mr. J. L. Wortman in a calcareous nodule 

 in the Wasatch formation of the Big-Horn basin, Wyoming Territory. 



Ckeodonta. 



Shortly after the publication of my arrangement of the Creodonta in 

 1880*, I obtained a good deal of additional material, which enabled me to 

 improve it in several respects. A number of genera have been added, and 

 the characters which distinguish the Miacidce and Oxycenidai have been 

 more fully brought out. The Miacidce, differ from all other families in 

 having the fourth superior premolar sectorial as in the true Carnivora, 

 while the true molars are tubercular. In Oxycena, the fourth superior pre- 

 molar displays no indication of sectorial structure, the first true molar 

 assuming that character. In Stypolophus and allies, the second superior 

 true molar is more or less sectorial, and the first true molar and even the 

 fourth premolar in some of the genera, develop something of the same 

 character. . But there is every gradation between the triangular Didetphys- 

 like, and the sub-sectorial Pterodon-\i\s.e forms of the superior molars, in 

 this group of genera. 



The glenoid cavity of the squamosal bone presents differences in the 

 various genera of this sub-order. In Arctocyonidce (fide De Blainville), 

 Oxycenidai, and Mesonychklce, it is bounded by a transverse crest anteriorly, 

 as well as by the postglenoid posteriorly, while in the Leptictidce it is plane 

 and open anteriorly. In Amblyctonidce its condition is unknown. In 

 existing Carnivora this character is not very constant as a family defini- 

 tion ; it is best marked in the Felidce, and least marked in the Canidce. 

 Nevertheless there is a group of genera allied to the Oxycenidce, which are 

 very marsupial in character, which have been called the Leplictidw, and 

 which differ so far as known from Oxycena in the absence of the preglenoid 

 crest. I suspect that these forms constitute a family by themselves, and 

 for the present, until our knowledge of them is fuller, I define it by this 

 character. The definitions of the families will then be as follows : 



I. Ankle-joint plane transversely, or nearly so.. 



True molars above and below, tubercular ; last superior not transverse 



Arctocyonidce. 

 Superior true molars, tubercular ; last superior premolar sectorial ; first 



inferior molar ' ' tubercular sectorial " . Miacidce. 



Superior last molar transverse ; inferior molars tubercular-sectorial or with 



reduced anterior cusp ; no preglenoid crest Leptictidce. 



Last superior molar trenchant, transverse; first superior true molar sec- 

 torial ; inferior .true molars tubercular-sectorial ; a preglenoid crest. . . 



Oxycenidce. 



* Proceedings Amer, Philos. Society, p. 76. 



