Fomily CRICETIDAE 169 



southward to extreme northeastern Mexico and Florida, fig. 93. 

 It also includes an extension into southeastern Kansas. 



SIGMODON HISPIDUS Say b Ord 

 Hispid Cotton Rat 



The cotton rat is known no closer to Illinois than Reelfoot 

 Lake in western Tennessee. The species is included in the key 

 because of the possibility, although remote, that it may occur in 

 southern Illinois. 



NEOTOMA FLORIDANA (Ord) 

 Eastern Wood Rat 



Description. — The eastern wood rat, fig. 94, is about the 

 size of a large Norway rat. The back and head are a brownish 

 gray or buffy gray, mixed with black, the under parts are white, 

 and the tail is blackish above and dull white below. The eyes 

 are large and black. The sides of the face may be grayer and 

 the legs more brownish than the back. The ears are large and 

 thin, and the tail is nearly as long as the body. 



Length measurements: head and body 8-854 inches (203-209 

 mm.); tail 7^-8 inches (187-203 mm.); over-all \5]4-l6]4 

 inches (390-412 mm.) ; hind foot about \}/2 inches (36-40 mm.) ; 

 ear from notch U/s inches (28 mm.). 



The skull is 39^2 mm. (about l]/? inches) long, has a long 

 rostrum, and has high cheek teeth, each of which has a smooth 

 grinding surface consisting of a series of triangles, fig. 74^. 

 Dental formula: I 1/1, C 0/0, Pm 0/0, M 3/3. 



Life History. — The wood rat in southern Illinois is an inhab- 

 itant of the cliffs and rocky bluffs, fig. 95, overlooking the bot- 

 tomlands of the Mississippi River. It lives in the crevices and 

 fissures within the cliffs and bluffs and among the rocky litter 

 at the base of these. It packs quantities of materials — sticks, 

 leaves, corncobs, cans, jar lids, empty shotgun shells, dung, or 

 almost anything else it can carry — to the nest. Buried within 

 this mass of rubble is the nest itself, measuring about 9 inches in 

 diameter and composed of masses of soft material. 



Little is known about the life history of the wood rat in Illi- 

 nois. Fifty miles south, in Tennessee, it is known to breed in 

 March and give birth to two or three young per litter in April. 



