BAILEY — BEAN MOUSE OF LEWIS AND CLARK 
71 
All efforts to determine which of the fifteen species of so-called mice 
of that region was responsible for the storing of the beans and artichokes 
have previously failed. Neither Indians nor white men who were 
familiar with the mice and their stores could agree on which was the 
storer even when they were shown specimens of all the species of mice, 
and their descriptions differed so widely as to add confusion rather 
than enlightenment. 
The Biological Survey field work in North Dakota has usually closed 
before the storing season begins, but in 1919 the work was so planned 
that I could remain late and make a special effort to get the mice with 
their stores. On October 30, at Cannon Ball, I found a small cache 
of beans and artichokes which I secured and also the mice with them. 
One was caught in a trap in a runway leading to the cache and one 
was taken alive in my hands as it ran out of the cavity where the 
stores were found not far from a soft nest, a few inches below the 
surface of the ground. 
While several other small rodents may also store the beans and arti- 
chokes the indications point to this as the one principally concerned 
in the accumulation of such food stores as are found along the Missouri 
River valley. Many specimens of these mice had been previously 
collected, so it was only necessary to connect the species with the stores, 
and somewhat to my surprise it proved to be a previously unrecognized 
subspecies of which I already had a description in manuscript. Fortu- 
nately this discovery was made in time to give the new form the name 
long used for it by the Indians. 
In working out the range of the Microtus pennsylvanicus group in 
North Dakota, I find specimens from numerous localities from the 
western part of the State that can not reasonably be referred to the 
large dark M. p. pennsylvanicus of the Eastern States, the little form 
M. p. drummondi of Canada and central North Dakota, nor to the dark 
gray ikf. p. modestus of the Rocky Mountain Region, although these 
three forms approach and evidently intergrade. A large pale form, 
most resembling modestus, is found to occupy the badland region of 
western North Dakota and eastern Montana. It occupies an extensive 
and well defined faunal subdivision of the Upper Sonoran and Transition 
Zones in the arid badland area of the northern Great Plains. While 
the limits of its range have not been fully worked out, the most typical 
and strikingly marked specimens are from the sagebrush and badland 
area of the Upper Missouri and Yellowstone Valleys. My first acquain- 
tance with the species was in 1913, when on the side of a badland butte 
