160 CLASS MAMMALIA. 



of the Academy of Natural Sciences of Philadelphia, pub- 

 lished in the present year, (1825,) named Neotoma. The 

 number of the teeth is 16 ; incisors §, cheek-teeth $, with 

 profound radicles. The angles of the ridges on the surface 

 of the cheek-teeth, which, together with the roots of these, 

 seem to found its principal pretensions to a generic sepa- 

 ration, are sufficiently marked by the figures. The grind- 

 ing surface of the molares, say its describers, differs some- 

 what from that of the molares of the genus Arvicola, as 

 will be perceived by our figures, but the large roots of the 

 grinders constitute a character essentially different. The 

 folds of enamel which mark the sides of the crown do not 

 descend so low as the edge of the alveolar processes ; in 

 consequence of this conformation, the worn down tooth of 

 an old individual must exhibit insulated circles of enamel 

 on the grinding surface. This genus, or sub-genus, must be 

 placed near to Arvicola. 



The Neotoma Floridana, (Florida Rat), has an elongated 

 snout ; eyes and ears very large, and tail longer than the 

 body ; the ears are large, thin, subovate, clothed with such 

 fine hair as to appear naked ; the whiskers are long ; the 

 body and head are lead-coloured, intermixed with yellowish 

 and black hair, the black predominating on the ridge of 

 the back and top of the head ; the yellow, on the sides, 

 abdomen, and throat; buff-colour belly, and claws white. 

 It measures between seven and eight inches, and the tail 

 above six. The whole fur is extremely soft and fine. 



It was found in East Florida, and its describers conclude 

 their notice by observing, that though the multiplication of 

 genera has become an evil, they have ventured to separate 

 it, from an inability to class it under any of the genera of 

 the systems. 



The genus Spalax, of Guldenstaedt, is another separa- 

 tion from the comprehensive genus Mus, of Linnaeus. 



