When Bole and Moulthrop named _Synaptomys cooperi saturatus_, with type locality in Illinois, they, in effect, divided the geographic range of _Synaptomys cooperi stonei_ into two parts (see A. B. Howell, N. Amer. Fauna, 50:10 (fig. 2), August 5, 1927) since Bole and Moulthrop (_op. cit._) did not assign to any subspecies the specimens from southern Wisconsin that Howell (_op. cit._) had identified as _S. c. stonei_. Bole and Moulthrop's inclusion in their newly named subspecies of a specimen from as far west as East Columbia, Missouri, left in doubt the subspecific identity of specimens from Iowa and a specimen from Arkansas. Howell (_op. cit._) had assigned this material from Iowa and Arkansas to _S. c. gossii_. Howell recognized that the one individual (168266 USBS) from Lake City, Arkansas, was too young to be identified to subspecies with certainty and assigned the specimen to _S. c. gossii_ "upon geographical grounds" (_op. cit._:19). Keith R. Kelson and one of us (Hall) compared this specimen with pertinent materials. As a result of this comparison we refer the specimen, on the same grounds employed by Howell, to _Synaptomys cooperi saturatus_. Specimens from approximately the southern half of Wisconsin (from Kelly Lake southward) were referred to _S. c. stonei_ by Howell (_op. cit._:16). Now that _S. c. saturatus_ has been recognized, these specimens from southern Wisconsin would be expected to be referable to _S. c. saturatus_. When these specimens were examined and compared (by Hall and Kelson) with other specimens in the United States National Museum the skulls were found to be much larger than in _S. c. cooperi_, smaller than in _S. c. gossii_, and nearly the size of those of _Synaptomys cooperi saturatus_, to which subspecies we refer the specimens in question. Howell (_op. cit._:16) referred a specimen from Cassopolis, Michigan, a locality that might be presumed to fall within the range of the more recently named _S. c. saturatus_, to _S. c. stonei_. Bole and Moulthrop did not mention this specimen when they described and named _S. c. saturatus_ (1942). Neither did Burt, but Cassopolis is within the geographic range ascribed to _S. c. cooperi_ on his map (The Mammals of Michigan, Univ. Michigan Press, p. 213, 1946). Examination (by Kelson and Hall) of the specimen (41777 MCZ) reveals that it resembles _S. c. cooperi_ in shortness of hind foot (18 mm.), shortness of tail (18 mm.), narrowness across zygomata (16 mm.), and grayish pelage. In the long braincase, heavy rostrum, greater condylobasilar length, greater lambdoidal breadth, long rostrum, and longer incisive foramina, it agrees closely with specimens of _S. c. saturatus_, to which subspecies we refer the specimen.