162 ON THE GEOLOGY AND NATURAL HISTORY 
Cretaceous formation No. 3, form lofty vertical walls, which are sometimes completely 
covered with their nests. A single shot is usually sufficient to supply one with all the 
specimens he could desire. 
COTYLE RIPARIA, Boie. 
Bank Swattow. Baird, General Report on Birds, p. 313. 
The vertical banks of yellow marl which are so conspicuous from the mouth of the Platte 
to the Niobrara, furnish excellent places of resort for this bird. Not unfrequently, this 
and the preceding species will be associated in the same cliff, the C. riparia in the surface 
deposit of yellow marl, while the H. lunifrons attaches its nest to the harder rocks below. 
Both this and the preceding species are universally diffused throughout North America. 
PROGNE PURPUREA, Boie. 
PurrLe Martin. Baird, General Report on Birds, p. 814. 
Most abundant throughout the Northwest, along the wooded bottoms of streams, where 
the dry trees are its favorite breeding-places. They do not usually remain longer than the 
months of May and June. 
AMPELIS. CEDRORUM, Baird. 
Cepar Birp. Baird, General Report on Birds, p. 818. 
Abundant everywhere in the Northwest. A second species, A. garrulus, will doubtless 
be found in great numbers in the mountains, as it occurs so abundantly near Fort Bridger. 
Mytapestes Townsenpu, Cab. 
TOWNSEND’s FrycaTcHEr. Baird, General Report on Birds, p. 321. 
Seems to be confined, as far as our observations extended, to the vicinity of the moun- 
tain ranges. Specimens were obtained at Laramie peak and the Black hills. 
COLLYRIO BOREALIS, Baird. 
Great Norruern Surixe. Baird, General Report on Birds, p. 824. 
Not uncommon from Council bluffs to Fort Pierre, especially during the winter. Lieut. 
Warren collected one specimen near Fort Pierre, and had it been abundant above that 
point, our party would have obtained other specimens. 
COoLLYRIO EXCUBITOROIDES, Baird. 
WHITE-RUMPED Surixke. Baird, General Report on Birds, p. 827. 
This species, unlike the preceding, seems to be quite abundant, especially along the 
Platte to the Laramie mountains, Black hills, and Bad Lands. It is very abundant in the 
hills about Fort Laramie. 
VIREO GILYUS, Bonap. 
WaARBLING FLycaTcHER. Baird, General Report on Birds, p. 335. 
Abundant along the wooded bottoms of the Missouri. 
