RODENTIA. 



PARAMYS, Leidy. 



" Extinct Vertebrate Fauna of the Western Territories," vol. i. Hayden's Sur- 

 veys, p. 109 et set/. 



THIS genus of the gnawers is very closely allied to the 

 squirrels and marmots. Dr. Leidy sums up the generic char- 

 acteristics of the teeth thus : 



" The four lower molars are proportionately narrower than 

 in squirrels and marmots, the fore and aft exceeding the 

 transverse. The crowns are short, square, tuberculate, and 

 enamelled. 



" The lower jaw is proportionately shorter and deeper than 

 in most known rodents; the reduction in length being mainly 

 due to a less development of that part of the bone in advance 

 of the molars. To compensate for the difference in length, 

 and to make room to accommodate the incisors, these teeth 

 reach further back than usual. 



" The acute edge of the hiatus between the molars and in- 

 cisors is almost on a level with the alveoli, of the teeth, instead 

 of forming a deep concave notch, so conspicuous a feature in 

 the jaws of the gnawers generally." 



Species known. 



{PARAMYS DELICATUS, Leidy. 

 PARAMYS DELICATIOR, Leidy. 

 PARAMYS DELICATISSIMUS, Leidy. 

 PARAMYS ROBUSTUS, Marsh. 



Am. Journ. Sc. v. iv., p. 218. 



