1883] NATURAL SCIENCES OF PHILADELPHIA. 77 



0!f THE MUTUAL RELATIONS OF THE BUNOTHERIAN MAMMALIA. 

 BY E. D. COPE. 



The name Bunotheria was proposed b}' me for a series of 

 Mammalia which resemble in most technical characters the Eden- 

 tata and the Rodentia. That is, the^^ agree with these orders in 

 having small, nearly smooth cerebral hemispheres, which leave 

 the olfactory lobes and cerebellum entirely exposed, and in somie 

 instances the hemispheres do not cover the mesencephalum also. 

 From the two orders in question, however, they are easily distin- 

 guished. Their enamel-covered teeth separate them from the 

 Edentata, while the articulation of the lower jaw is different from 

 that found in the Rodentia. It is a transverse ginglymus, with 

 a postglenoid process in the Bunotheria, as distinguished from 

 the longitudinal groove, permitting anteroposterior motion, of the 

 Rodentia. 



Such a group as is thus characterized will include two existing 

 groups recognized as orders — the Prosimiae and the Insectivora. 

 The latter group has always been a crux to systematists, and 

 when we consider the skeleton alone, as from the standpoint of the 

 palaeontologist, the difficulty is not diminished. Various extinct 

 types discovered in latter years, chiefly in the Eocene formations, 

 have been additions to this intermediate series of forms, giving 

 even closer relations with the orders already adjacent; i. e., the 

 Edentata, the Rodentia, the Prosimiae, and the Carnivora. As is 

 known, the groups corresponding to these orders have been 

 named respectively the Taeniodonta, Tillodonta, Mesodonta, and 

 Creodonta. With great apparent diversity ,.these suborders show 

 unmistakable gradations into each other and the two recent orders 

 alread^y mentioned. As such, I may mention Psittacotherium, 

 which relates the Tseniodonta and Tillodonta ; JEsthonyx, which 

 relates the Tillodonta with nearly all the other suborders ; 

 Achsenodon, which connects Creodonta and Mesodonta, and 

 Cynodontomys, which may be Mesodont or Prosimian. Then 

 the existing Ghiromys most certainly connects Tillodonta and 

 Prosimiae. 



My original definitions of the suborders of the Mesodonta, given 

 in vol. ii of the U. S. Geological Survey under Capt. G. M. 

 Wheeler, p. 85, omitted the Prosimiae, and embraced a number 



