Fes., 1912. MamMats oF ILLINOIS AND Wisconsin — Cory. 233 
Genus SYNAPTOMYS Baird. 
Synaptomys Baird, Mammals N. Amer., 1857, p. 558. Type Synap- 
tomys cooperi Baird. 
Front of upper incisors (front teeth) with distinct groove near 
outer edge; molars without pronged roots; tail short; face of incisors 
orange brown in color; crowns of molars with transverse 
Wy loops. A North American genus comprising two subgenera, 
Synaptomys and Mictomys, but only the former is represented 
Front vey within our limits. The subgenus Synapiomys has the 
(enlarged). crowns of the lower cheek teeth (molars) with closed enamel 
triangles, a loop on the outer edge, and the mammez are 6. 
=, of Pim. aes M. 373 _ 16, 
I ° O° 
I- -o -o 37-3 
‘Dental formula: I. 
Subgenus SYNAPTOMYS Baird. 
Synaptomys cooperi gossii (MERRIAM). 
: Goss’s LEmuinc Movse. 
Synaptomys helaletes gossii MERRIAM, Proc. Biol. Soc. Wash., X, 1896, p. 60. 
Synaptomys gossi HowELL, Proc. Biol. Soc. Wash., XXIII, 1910, p. 30 (Missouri 
and southern Illinois). 
Synaptomys cooperi CouEs, Monog. N. Amer. Rodentia, 1877, p. 235-236 (part) 
(southern Illinois). OsBorn, Proc. Iowa Acad. Sci., I, 1887-89 (1890), p. 43 
(Iowa). Woon, Ill. State Lab. Nav. Hist., VIII, 1910, p. 559 (Champaign Co., 
IIL). 
Type locality — Neosho Falls, Woodson Co., Kansas. 
Distribution — Kansas, Missouri and southern Illinois, northward 
through at least a considerable portion of Illinois, lowa and Nebras- 
ka to South Dakota; range not satisfactorily determined. 
Description — Adult in summer: General color of upper parts dark 
rusty brown or reddish brown mixed with black tipped hairs; under 
parts plumbeous gray, the hairs with white tips but the plumbeous 
under fur showing through; a dusky mark at base of the whiskers; 
tail brownish above, paler beneath; skull larger and heavier and 
brain case actually and relatively longer than in cooperi. 
Adult in winter: Grayer and decidedly less reddish brown. Im- 
mature specimens are quite different, the general color of the upper 
parts being dusky slate or grayish brown according to age. 
Measurements — Total length, about 5 in. (128 mm.); tail vertebre, 
-7oin. (17.5 mm.); hind foot, .75 in. (r9 mm.). 
