104 



COPE 



Fig, 41. — Ptilodus medi<Bvus 

 Cope ; mandibular ramus ; a, b, 

 t; c, f. Original. FromPueroo 

 bed of New Mexico. 



Fig. 42. — Ohirox plieatus Cope ; palate and molar 

 teeth, from below, 3-2 natural size. From Puerco bed 

 of New Mexico. Original. 



America, and in the later Cretacic of North America 

 and of Patagonia. In the latest Cretacic (Puerco) of New 

 Mexico the largest forms occur, which equal an adult kan- 

 garoo (Figs. 41 and 42), The last of them are found in 

 the lowest Eocene in the north of France. Extinct and re- 

 cent MoNOTREMATA are restricted to the Australian realm. 



The EuTHERiA are represented by the following numer- 

 ous orders : 



I. Marsupial pelvic bones (generally) ; palate per- 

 forated ; (vagina double ; placenta wanting ; corpus 

 callosum rudimental ; cerebral hemispheres small). 

 {Didelphia.) 



One deciduous molar tooth shed ; the 



rest permanent ; (1) Marsupialia. 



II. No marsupial bones ; palate generally entire ; 

 (one vagina ; placenta and corpus callosum* well 

 developed). (Monodelphia.) 



A. Posterior limbs wanting, or represented by 



» More recent researches than those of Osborn in 1886, confirm the view of Owen 

 that this element is the hippocampal commissure. ^H. F. O. 



