ORDER II 



MARSUPIALIA 



25 



Ptilodus Cope (Chirox Cope) (Fig. 33). 



1.1.4.2. 



Skull depressed and flat 



1.0.2.2. 



with a long, broad snout, palate with large foramen, and articular condyle 

 situated near the broadly expanded occiput. Upper C resembling I but 

 smaller, P^ with three, P'^ with four, P'^ with six tubercles, and P^ elongated, 

 with numerous tubercles. M^ narrower than P^. P^ reduced, P^ strongly 

 developed, and grooved on both sides. M-^ with more numerous tubercles 

 than 31.-,. Humerus massive, with small entepicondylar foramen. The pelvis, 

 femora, and lower limb-bones are also known. Lowest Eocene ; Montana and 

 New Mexico. 



Cimolomys Marsh (Ciinolodon, Nanoimjs Marsh, Ptilodus, Halodon Osborn) 

 (Fig. 34). Upper M with three rows of tubercles. Upper Cretaceous 

 (Laramie) ; Wyoming and Montana. Middle Cretaceous of North-West Canada. 



Meniscoessiis Cope {Dipriodon, Tripriodon, Selenacodon, Oracodon Marsh) 

 (Fig. 35). Isolated teeth are practically the only known remains. Upper M 

 with three rows of tubercles. Upper Cretaceous (Laramie) ; North America. 

 Wealden ; England. 



Family 3. Polymastodontidae Cope. 



Both jaws with a strong, rodent-like I on each side and two large M, in front of 

 which is a small, simple P, separated from the I hy a long diastema. The large 

 upper I followed hy a sinall I. The lower M 

 have two, the upper three longitudinal series 

 of stout tubercles. Angle of lower jaw in- 

 flected. Articular condyle lying almost in the 

 occipital pilane. Basal Tertiary (Puerco) ; 

 New Mexico. 



Polymastodon Cope (Taeniolahis, Catop- 



2.0.1.2. 

 safe Cope) (Fig. 36). . Attaining 



about the size of a beaver. 



Fig. 35. 



A, MeniscoHssus conquistus Cope. Upper molar from the 

 Upper Cretaceous (Laramie formation) of Dakota ; ^/j (after 

 Osborn). jS, Tripriodon coelatus Marsh. Upper Cretaceous 

 of Wyoming. Probably the last upper molar, i/i a^nd 2/j 

 (after Marsh). 



Fig. 36. 



Polymastodon attenuatus Cope. Lowest Eocene 

 of New Mexico. Palate with both tooth rows, 

 i/l. (After Osborn.) 



Polydolopidae Ameghino. 

 P^, P^ and lower P 



Family 4. 



Lower I almost horizontal, 

 frequently developed to form a cutting surface. Upper 

 tubercles, lower always with two only and diminishing in size posteriorly. 



1.0.2.3. 



ofte7i five tubercles in a row. ' ' ^ ' . Early Tertiary ; Patagonia 



^ higher than M and most 

 M with two or three series of 



Three, less 



