204 Bergtold, The Crow in Colorado. Anril 



LApril 



Resume. 



I. — It can now be said categorically that the Crow occurs in 

 Colorado in the guise of two subspecies, viz., brachyrhynchos and 

 hespcris, both being found on the eastern slope, and only the latter 

 on the western slope of the Rocky Mountains. 



11. — The above conclusion stands if my determinations of the 

 skins 1 have studied be correct; if my determinations be incorrect 

 they show that the criteria by which these two subspecies are 

 differentiated, are too subtile and refined for an ordinary ornitholo- 

 gist like myself to grasp and apply, or that the described differences 

 between these two subspecies break down with the Crows found 

 in Weld County. 



Measurements of hespcris skins (8: millimeters). 



Bill 

 Locality Sex Wing Tail Length Depth Tarsus 



Bibliography. 



1. Aiken: Proc. Boston Soc. Nat. Hist., XV, p. 193 et seq. 



2. Ridgway: Field and Forest, June 1877, p. 208. 



3. Stephens: Bull. Nutt. Ornith. Club, iii (1878), p. 94. 



4. Drew: Bull. Nutt. Ornith. Club, vi (1881), p. 143, and Auk, Jan., 



1885, p. 16. 



5. Ridgway: Man. N. A. Birds, 1887, p. 362. 



6. Auk: July, 1908, p. 348. 



7. Ridgway: Birds No. and Mid. America, vol. iii, p. 270 et seq. 



8. Morrison: Ornith. and Oologist, July, 1888, p. 107. 



9. Morrison: Ornith. and Oologist, xiv (1889), p. 147. 



10. Cooke: Condor, July, 1912, p. 147. 



11. Hersey and Rockwell: Condor, xi (July-Aug. 1909), p. 118. 



12. Warren: Condor, Jan. 1910, p. 34. 



13. Sclater: Birds of Colo., 1912. 



14. Warren: Condor, Jan. 1909, p. 15. 



