a new genus of the order Rodentia, 335 



the anterior corner of the second one, and exists in the adult animal. 

 The rest of the grinders are perfectly simple in their structure, without 

 roots, have slightly concave crovms, and are simply cased in enamel, 

 without any transverse ridges or eminences. There is an acute 

 vertical ridge on the exterior side of the upper grinders, and 

 inner side of the lower ones, vnth a wide furrow or groove on each 

 side of it, and the opposite side of the tooth is rounded or semicircular. 

 The second grinder in the upper jaw, and the first in the lower, are a 

 little larger than the others, and the former has a projection of enamel 

 at its anterior corner, producing a second, though smaller, perpendicular 

 ridge, within which the small first grinder is situated. There is a slight 

 ftirrow on the exterior sides of the lower grinders, most conspicuous in 

 the first one. 



Palate narrow ; the right and left rows of grinders being near each 

 other, and disposed in parallel straight lines. 



Head flat and broad ; nose a little arched, thick and obtuse. 



Lower jaw thick and strong, much developed posteriorly, and having 

 condyles more transverse than longitudinal. 



Cheek-pouches none. 



Eyes very small. Ears short and rounded, approaching in form to 

 the human ear. 



Body thick and short. 



Limhs short and thick; feet moderately strong, vdth naked soles. Five 

 toes on all the feet, rather short, but well separated. The thumb of the 

 fore-feet is considerably shorter than the other toes. Claws, particularly 

 the fore ones, very long, strong, much compressed, and but little curved. 



Tail very short, concealed by the fur of the hips. 



MammcB six, the anterior pair between the fore-legs. 



Habit. The Sewellel is a plantigrade, burrowing animal, living in 

 villages, and feeding on vegetable substances. 



Aplodontia Leporina. The Sewellel. 



Sewellel. Lewis and Clark' sJoMmey, &c. iii, p. 39, (Engl, ed.) 

 Anisonyx ? rufe. Rafinesque, Desm., Mamm, p. 330,. in notis. 



z 2 



