_Specimens examined_ (22).--NE 1/4 sec. 22, R. 1 E, T. 23 N, 1; 7 mi. N,
2-1/2 mi. W Camp Crook, 3300 ft., 3; Camp Crook, 1; 10 mi. S, 5 mi. W
Reva, 10; 10 mi. S, 4 mi. W Reva, 4; 2 mi. S, 5 mi. E Harding, 2; Crow
Buttes, 1 (USNM).
The northern pocket gopher probably occurs in most areas of northwestern
South Dakota where the soil is sufficiently deep for constructing
burrows, but we found it commonest in the lower grassy slopes of buttes
and in relatively sandy areas along some of the major streams.
A female obtained on June 20 contained two embryos that measured 3.
Testes of an adult male trapped on May 18 measured 19 and those of one
taken on July 6 measured 9. Juveniles were collected in both May and
June.
Bailey (1915:102) referred a specimen from Crow Buttes to _T. t.
bullatus_, but Swenk (1941:3), in the original description of _T. t.
pierreicolus_, suggested that this same specimen "probably" was
referable to the latter because he assumed it came from soils of the
Pierre series. However, Baker (1952:8) included the Crow Buttes in the
Hell Creek formation and, in any event, one of us (Jones) examined the
specimen in question and found it clearly referable to the subspecies
_bullatus_. Over and Churchill (1945:32) erroneously assigned pocket
gophers from northwestern South Dakota to two different subspecies
(_bullatus_ and _clusius_), referring at least one individual from
Harding County to _T. t. clusius_.
Fleas, _Dactylopsylla ignota_ (Baker), were found on one individual
examined. Molting adults were taken in each month from May through
August.
~Perognathus fasciatus fasciatus~ Wied-Neuwied, 1839