546 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



regions with reference to anticipated publication in connection with the 

 official report of the United States Boundary Commission; but the 

 present is hardly the place to present these considerations in detail. 

 I may, however, state that my results agree closely with those derived 

 from the geological investigations made by Mr, George M. Dawson, my 

 colleague of the British contingent of the Survey, whose valuable Report 

 should be consulted in this connection, and that they are in striking 

 accord with what would be the geographer's or the topographer's con- 

 sideration. 



1. Bed River region, or watershed of the Eed and Mouse Elvers. At 

 490 this extends westward along the northern border of Dakota, nearly 

 to Montana, — to the point where the Coteau crosses the Line. The bird- 

 fauna of this region is decidedly Eastern in character, — much more so 

 than that of the portion of the Missouri Basin which lies south of it and no 

 further west. It is well distinguished, both by this Eastern fades and by 

 the absence of the species which mark the Missouri region. The region 

 consists of more or less (nearly in direct ratio as we pass westward) fer- 

 tile prairie, treeless except along the streams, cut by the two principal 

 river- valleys, the Eed and the Mouse, crossed by the low range of the 

 Pembina Mountains, ahd marked by the isolated butte known as Turtle 

 Mountain. It is bounded to the west and south by the Coteau, — a com- 

 paratively very slight ridge, which nevertheless absolutely separates 

 the two great watersheds. The Eed Elver flows nearly due north; the 

 Mouse Eiver makes a great horseshoe bend, at first directed toward the 

 Missouri, which it almost reaches before it is "bluffed off", literally, and 

 sent northward.* The bird faufia of Pembina and the whole immediate 

 Eed Eiver Valley is thoroughly Eastern. The only Western trace I ob- 

 served was Bpizella 'pallida and some Icteridw, especially Scolecoplcagus 

 eya7iocephalus ; though Sturnella neglecta and XantJiocephalm icteroceplia- 

 lus are both common prairie birds much further east, as Pedicecetes go- 

 lumhianus also is. Characteristic mammals are Speronophilus IS-Uiieatus, 

 S. franMini, Tamias quadrivittatus, Thomomys talpoides, and the rare 

 Onychomys leucogaster. Out on the prairie, beyond the Pembina Mount- 

 ains, this region is distinguished by the profusion of several very nota- 

 ble birds, — Anthus spraguii, Plectrophanes ornatus, Passerculns hairdi, and 

 JEremopJdla leucolwma, all breeding, none of them observed at Pembina. 

 Here also was found Coturniculus lecontii. This treeless area is fur- 

 ther marked by the absence of sundry birds common enough in the 

 heavily-timbered Eed Eiver Valley, as PJmpidonaces, Vireones, Antrosto- 



* Fort Pembina is situated on the Eed Kiver, latitude 49° nearly ; longitude 97° 13, 

 42" west; altitude 790 feet above sea-level. The Pembina Mountains, well wooded, 

 with a maximum elevation of about 1,700 feet, lie 35 miles west of the Eed Eiver, 

 forming an escarpment which separates the low immediate valley of the Eed Eiver 

 from the next higher jirairie steppe, which reaches to the Coteau. Turtle Mountain is 

 an isolated, heavily- wooded butte, 125 miles west of Pembina, with an elevation of 

 about 2,000 feet above sea-level, lying directly on the parallel of 49°. Our camp, at 

 its west base, was in longitude 100° 30' 41.1", distant 149,25 miles from Pembina along 

 the parallel. 



