12 U. S. P. R. R. EXP. AND SURVEYS—ZOOLOGY—GENERAL REPORT. 
Sub-Genus Gennaia. 
FALCO POLYAGRUS, Cassin. 
Falco polyagrus, Casstx, B. of Cal. and Texas, I, p. 88. (1853. ) 
Ficures.—Cassin, B, of Cal. and Texas, I, pl. 16. 
Narrow frontal band, line over the eye and entire under parts white; stripe from the corner of the mouth running 
downwards, dark brown; breast and abdomen with longitudinal stripes and spots of brown, which color forms a large and 
Conspicuous spot on the flank. Upper parts brown, paler on the rump; tail above pale grayish brown, narrowly tipped 
with white, and with transverse bands of white; quills dark greyish brown; edge of wing at the shoulder and below 
white, spotted with brown. Bill bluish ; under mandible yellow at base ; space around the eye bare, with a narrow edging 
of brown on the first plumage around it, the brown of the back extending somewhat on to the breast at the wing. 
Younger. Frontal band nearly obsolete ; upper parts uniform pale brown, with narrow rufous stripes on the head ; under 
arts white, tinged with dull! yellow, nearly every feather having a longitudinal stripe of dark brown; large spaces on the 
flanks brown; tarsi and toes lead colored. 
Total length 18 to 20 inches, wing 13 to 14, tail 74 to 8 inches. 
Hab. Western North America. Spec. in Nat. Mus, Washington, and Mus. Acad. Philadelphia. 
This is exclusively a species of Western North America, but extending its range east of the 
Rocky mountains, several specimens having been obtained during the exploration of the upper 
Missouri and Yellow Stone rivers by the party commanded by Lieutenant G. K. Warren, 
United States army. A specimen of this species has, also, been recently procured in western 
Illinois by Mr. J. D. Sergeant, of Philadelphia. 
Adults of both sexes are very similar, in fact not differing except in size, and are almost pre_ 
cisely as described and figured by us as above. 
It is possible that this may be the specices described as Falco mexicanus in 1850 by Schlegel, 
but I have been unable to make a reference to his article. 
List of specimens. 
| Measurements. 
5 . Samii) sale 
2 Fy S |3 8/5 
5 al Locality. When collected. | Whence obtained. | 2 Nature of speci-| Collected by— | = c2/5 
3 = =alae 
8 Ep 2 men. BSifSaul/g 2 
& | = | z sslgeles 
a = S =e BS 3 
s “ = 4=| ee |] oo 
5 | a 5 * 2 |g*lz 
OLG9)|\...... Mouth of Knife river, Mo. river...| Sept. 10, 1856....) Lieut. Warren 19.00 45.50) 13.50 
5168 Q Knife river, Missouri...........-- | Sept. 16, 1856....)........ do:y.. 18.25 49.95] 13.75 
5167 Q Fort Randall, Nebraska... ball Oct. 17, 1856... Be CO ayaa -| 19.00 49.00 13,50 
5951| GN. Platte, Nebraska..... .| Aug. 20, 1857....- Lieuts Bryanacesees|(429) llneccsaceseases os |, WeSeaWoor cul ccesac\ees oon ee 
8502 [o) Fort Thorne, New Mexico......... Dr. T.. 0. Henry.... 
8503 |..-..- Camp on Little Colorado......... Lieut. Whipple.... 
8504 QO Fort Dalles, Oregon Territory Dr. Suckley........ 
ABS] |. eeeee Presidio, California. .......... Lieut. Trowbridge . 
5482 _ Petaluma, California FE. Samuels........ 
