Unquestionably the easiest route of migration into the St. George area is down the Virgin River from Zion National Park; no barrier to gophers occurs between the Park and St. George. Although the animals from St. George are all intergrades, the majority of their affinities as would be expected are with _planirostris_ from Zion National Park. The river itself is not an impassable barrier for gophers to the north and south of it, since this stream frequently changes its course, and often nearly dries up. The Virgin River Valley in Zion National Park is in the bottom of a relatively deep, narrow canyon which has sheer rock escarpments. The upper reaches of the river are inhabited by pocket gophers of another species, _Thomomys talpoides_. Two specimens from St. George, north of the Virgin River, were identified as _centralis_ by Hall and Davis (1934:52), but were stated to be intergrades between _centralis_, _trumbullensis_ and _planirostris_. Goldman (1938:338) referred twelve specimens from St. George to _nicholi_, but stated that they intergraded with _planirostris_. Twenty-six other specimens from three miles southwest of St. George on the west side of Santa Clara Creek, about one-half mile above its confluence with the Virgin River and on its north side, like the topotypes of _planirostris_ were taken in May and have complete, fresh summer pelage. With the exception of two specimens which show the ventral color of _virgineus_, these animals are indistinguishable in color from the topotypes of _planirostris_. A study of eleven measurements of the males of this series yield the following data: Like _planirostris_ in four measurements, _birdseyei_ in one, _virgineus_ in one; intergrade between _planirostris_ and _birdseyei_ in two, _planirostris_ and _virgineus_ in two and _birdseyei_ and _virgineus_ in one. Corresponding measurements of the females show the animals to be: Like _planirostris_ in four measurements, _birdseyei_ in one, _virgineus_ in two; intergrade between _planirostris_ and _birdseyei_ in two, _planirostris_ and _virgineus_ in one and _birdseyei_ and _virgineus_ in one. In eight of eleven measurements the males either are like _planirostris_ or intergrade towards it, and the females are similarly allied to _planirostris_ in seven out of eleven measurements. In none of the measurements was either sex referable to _trumbullensis_.