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GENUS NEOTOJIA.— Say et Ord. 



DENT.VL FORMULA. 



Incisive g-; Canine ^^■, Molar g^ = 16. 



Messrs. Say and Ord, who established this genus, having given an ex- 

 tended description of its teeth, &c., we shall present a portion of it in 

 their own words. 



" Molars, with profound radicles. Superior jaiv — Incisors even and 

 slightly rounded on their anterior face : first molar with five triangles, 

 one of which is anterior, two exterior, and two interior. Second molar 

 with four triangles ; one anterior, two on the exterior side, and a very- 

 small one on the interior side : third molar with four triangles ; one an- 

 terior, two exterior, and a very minute one, interior. 



" Inferior jaw. — Incisors even, pointed at top : first molar with four di- 

 visions or triangles, one anterior, a little irregular, then one exterior, one 

 interior opposite, and one posterior : second molar, with four triangles an- 

 terior and posterior, nearly similar in form, an intermediate one opposite 

 to the interior and exterior one : third molar with two triangles, and an 

 additional small angle on the inner side of the anterior one. Tail hairy ; 

 fore-feet, four toed, with an armed rudiment of a fifth toe : hind-feet, 

 five toed. 



OBSERVATIONS, 



The grinding surface of the molars differs somewhat from that of the 

 molars of the genus Arvicola ; but the large roots of the grinders consti- 

 tute a character essentially different. The folds of enamel which make 

 the sides of the crown, do not descend so low as to the edge of the al- 

 veolar processes ; in consequence of this conformation, the worn down 

 tooth of an old individual must exhibit insulated circles of enamel on 

 the grinding surface." 



Neotoma — Gr. nut, (neos,) new ; and Tif/.va, (temno,) I cut or divide. 



Two species of this genus have been described, both existing in North 

 America. 



