298 Messrs. Say and Ord on Sigmodon hispidum. 



In respect to its generic affinities, it is very obvious that its 

 system of dentition indicates a proximity to Arvicola, but the 

 diiFerent arrangement of the folds, and the circumstance of the 

 molares being divided into radicles, certainly exclude it from that 

 genus. With respect to radicles, it resembles the genus Fiber ; 

 but it is allied to this genus in no other respect. 



We may further remark, that the teeth of our specimen are 

 considerably worn, a condition that materially affects the depth of 

 the folds. 



S, hispidum. Head thick; snout elongated; eyes pretty 

 large ; ears large, round ; tail nearly as long as the body. 



Ears slightly clothed with hair : fore legs short : hind feet 

 large and strong, their lateral toes very short, and their claws 

 stout ; upper parts and head of a pale dirty yellow ochre, mixed 

 with black : lower parts cinereous ; hair of the upper parts and 

 sides, long, plentiful and coarse. 



Length from the tip of the snout to the insertion of the tail, six 

 inches; tail four inches long. Female. 



In immature specimens, black is the predominating colour ; in 

 adults yellow predominates. 



This animal we found to be very numerous in the deserted 

 plantations, lying on the river St. John, in East Florida, par- 

 ticularly in the gardens. Its burrows are seen in every direction. 

 Emigrants to that section of our country will, doubtless, find this 

 species to be a great pest in rural economy. 



We brought three specimens of it from East Florida in 1818^ 

 and deposited them in the Philadelphia Museum. This animal 

 appears in classification to occupy a station between the genera 

 Arvicola and Mus^ having the habits and some of the external 

 characters of the former, with teeth remotely allied to the latter. 

 After a careful perusal of those authors within our reach, who 

 have laid down the characters of Mammiferous quadrupeds, par- 

 ticularly Mr, F. Cuvier's recent work, entitled " Des Dents des 

 Mammijeres considerees cotume characteres Zoologiques," we have 

 found ourselves under the necessity of constructing a genus for it, 

 it being impossible to refer it to any one of the genera, the 



