542 MONOGRAPHS OF NORTH AMERICAN RODENT! A. 



This form of the genus appears to have been first noted hy Dr. Wood- 

 liouse in 1853. His specimens were from El Paso. The known limits of its 

 distribution were enlarged in 1857 to include the region of the Platte; while 

 specimens still more recently examined show that it extends northward to the 

 Yellowstone at least, further east in Dakota, Nebraska, and Kansas than was 

 formerly supposed, and even reaches to Arkansas, where specimens were 

 lately procured at Fort Cobb. 



Note. — The special papers in which the Saccomyidee have been treated 

 will be found quoted passim in this article; these citations constituting that 

 portion of the bibliography of the family which I have compiled. 



