Cope.] 4/0 [Oct. 20, 



period, and extended through the Cretaceous. It is represented in the 

 latter period in the Laramie by the genus Meniscoessus.* 



In the absence of a number of the existing orders of placental Mammalia, 

 the Puerco agrees with other Eocene faunae. In the absence of all of the 

 placental orders with convoluted cerebral hemispheres, this fauna is more 

 primitive than any other Eocene fauna. The absence of all ungulata ex- 

 cepting Taxeopoda, which have the most primitive foot structure, is further 

 evidence of its primitive character. This is further increased by the pres- 

 ence of the Marsupialia above mentioned. The general result is a mix- 

 ture of Marsupial, and semi-marsupial forms, with half lemurs, and a 

 great expansion of the Hyracoid type. 



In more detail, the genera of Bunotheria may be compared with those of 

 the period immediately following ; viz. : The Wasatch. One genus only 

 of the Creodonta is common to the two epochs (Didymictis). Five of the 

 species v niaining are much like oppossums, and may be Marsupialia. The 

 two genera (Deltatherium and Triisodon) to which they belong, do not 

 occur in the Wasatch. The remaining two genera, (three species) are 

 peculiar to the Puerco, but represent a family (Mesonychidse) which 

 occurs throughout our Eocenes. The two species of Mesodonta belong to 

 genera of the Wasatch, one of them at least extending into the Bridger. 

 The genera of Tgeniodonta and Tillodonta are distinct from those of any 

 of the later Eocenes, so far as known. 



Supplement on a new Meniscotheriumfrom the Wasatch epoch, 

 Menisffotherium tapiacitis, sp. nov. 



The species now to be described is a good deal smaller than M. chameme, 

 and, a fortiori, than the M. terrmrubrm. It is known to me from the 

 nearly entire rami of a single mandible. These support the last five molars 

 of one side or the other, and alveoli of two others and of the canine tooth. 



Two characters besides the small size, are observable in this jaw. First, 

 the symphysis has not the shallow convex inferior outline in transverse 

 section ; but is on the contrary angular, having sub vertical sides separate 

 from a convex middle by a rounded angle. The symphysis is thus deeper 

 than in M. terrcerubros. Second, the crown of the third inferior molar tooth 

 has partly the form of that of the second of the M. terrmrubrce. It is antero- 

 posterior^ short, and has a short heel and no anterior basal lobe ; the sec- 

 tion of the principal lobe is lenticular, and profile subconic. In M. terra- 

 rubrce this tooth is elongate, with well developed heel and anterior lobe. 

 The alveolus of the canine is relatively larger than that of the M. terrozru- 

 bra. The coronoid process does not rise so close to the last molar tooth, 

 nor so steeply, as in the latter species. The posterior recurvature of the 

 internal extremity of the anterior limb of the posterior V of the true mo- 

 lars is but little marked. 



* American Naturalist, 1882, p 830, Sept, 28th. 





