90 Scott on Birds observed at Twin Lakes, Colorado. 
C. familiaris of Europe they vary from six to nine. The usual num- 
ber is six, which are placed in two rows of three, in this way best 
conforming to the oblong shape of the nest. 
The reasons given by Mr. Dresser for regarding Certhia familia- 
ris, C. brachydactyla , C. costas, C. americana , and C. mexicana as but 
closely allied races of a common species appear to be quite conclu- 
sive. European examples are found not distinguishable from the 
American. 
NOTES ON BIRDS OBSERVED AT TWIN LAKES, LAKE 
COUNTY, COLORADO. 
BY W. B. D. SCOTT. 
The following brief summary gives the results of some seven 
weeks’ work at the point above indicated. The time spent at this 
locality extended from June 12 to July 30, 1878, and the area ex- 
plored being small, only a limited number of species were observed. 
The Twin Lakes are situated in the valley of the Arkansas River, 
about a hundred and fifty miles southwest of Denver, and at an ele- 
vation of 9,265 feet above the sea. Five miles to the eastward of 
these lakes, and several hundred feet below them, flows the Arkan- 
sas River. Lake Creek, flowing from these lakes into the river, is 
one of its main branches at this point. The lakes are situated the 
one to the eastward of the other, the smaller of the two, a mile and 
a half long by a mile wide, being the western one. The larger 
lake is about three times the size of the other, and, like it, is 
oval in form. The two are not more than a quarter of a mile apart 
at their nearest point. On all sides, save to the eastward, the land 
rises very abruptly to the height of four or five hundred feet, and 
forms a sort of plateau from which at the distance of a mile rise 
mountains of different altitudes, some rather more and few less than 
fourteen thousand feet high. 
The land is sandy and rocky, having a considerable growth of sage- 
brush, and is, for this portion of the country, well wooded. The 
greater portion of the trees are pines, but in localities occur groves 
of quaking asp ( Popidus tremuloides ). These latter and some low 
willows along the outlet form the only deciduous trees. 
Without entering into any consideration, of what species may be 
attracted to this region at any other seasons than that of my visit, 
