IOWA ACADEMY OP SCIENCE 
203 
NOTES ON A COLLECTION OP MAMMALS PROM NORTHWESTERN IOWA. 
BY ALEXANDER G. EUTHVEN AND NOBMAN A. WOOD. 
The University of Michigan Museum has acquired a considerable number of 
specimens of mammals from Northwestern Iowa during the past five years. 
Most of the material was obtained by the expedition of 1907, but a number of 
specimens have been received from residents. The museum is particularly 
indebted to Mr. Nels Hansen, of Ruthven, Iowa, who has sent in a considerable 
amount of valuable material. 
The material obtained by the expedition was collected principally by Max M. 
Feet and A. G. Ruthven in the townships of Riverton, Sioux, Lake, Preeman 
and Logan, Clay County, and Lost Island and Highland, Palo Alto County.* 
The miscellaneous material was taken in the same region. The habitat data 
in the present paper is from the field notes of A. G. Ruthven. It should also 
be mentioned that the specimens of Peromyscus maniculatus bairdii, Microtus 
drummondi (?), Reithrodontomys griseus, Lepus campestris and Sylvilagus 
floridanus mearnsi have been examined and so determined by E. W. Nelson 
of the U. S. Biological Survey. 
LIST OF SPECIES. 
DidelpMs virginiana (Kerr). Virginia Opossum. — No specimens of this 
species were observed, but various hunters and residents informed the collectors 
of the expedition that it is occasionally found in the region studied and an 
authentic record was obtained for Gillett’s Grove, Gillett’s Grove Township, 
Clay County. Of its occurrence in Nebraska, Swenk** says, “The Opossum is a 
typical Carolinian animal which formerly was uncommon in this state and 
found only in the extreme southeastern portion, but of recent years it has 
extended its range along the wooded tributaries of the Missouri until it is 
now present along nearly the whole eastern edge of the state.” , It has probably 
entered the region studied by way of the timber zone along the Little Sioux 
River and tributary streams. 
Gitellus tridecemlineatus (Mitchell). Thirteen-striped Spermophile. — A series 
of twenty-seven specimens was obtained by the expedition. As was to be 
expected, the species is very common in this part of the state. It was found in 
every area of prairie and meadow land examined. The specimens are very 
large. The average measurements of four males are: length 286 mm., tail 
101 mm., foot 40 mm., and of seven females: length 277 mm., tail 96 mm., 
foot 40 mm., while the three largest Michigan specimens in the museum col- 
lection only average, length 260 mm., tail 85 mm., foot 36 mm. In color they 
cannot be distinguished from Michigan specimens. One individual was ob- 
served eating a house mouse which was covered with fresh blood. 
*For a description of the habitats in this region see Ruthven, A. G., Contributions 
to the Herpetology of Iowa, Proc. Iowa Acad. Sci., XVII, pp. 198-204. 
**A Preliminary Review of the Mammals of Nebraska. Studies from Zool. Lab. 
Univ. of Nebraska, No. 89, p. 14. 
