10 Birds of Colorado 
Museum, were slightly incubated and show the charac- 
teristic staining over the pale green. They are oval in 
shape, rather pointed at one end, and average about 
175 xX 1°20. 
Family GAVIIDZ. 
The characters of the family are the same as those 
of the only genus. 
Genus GAVIA. 
Bill stout, strong and compressed, about as long as the head ; no 
crests or ruff; tail short, of 18 to 20 stiff feathers ; legs feathered to the 
upper tarsal joint ; tarsus strongly compressed ; four toes, the three 
anterior completely webbed; the hallux very short with a small 
semicircular lateral lobe, and connected with the others by a basal 
web, plumage dusky above, white below. 
Five species from the northern portions of both hemispheres. 
Key oF THE SPECIES. 
A. Back spotted with white. 
a. Head and neck black. 
a’ Bill mostly black, white spots on the scapulars about 
square. G. immer, p. 10. 
b* Bill mostly yellow, white spots on the scapulars longer 
than broad. G. adamsi, p. 11. 
b. Head and back of the neck grey. G. arctica, p. 11. 
B. Back without spots. 
a. Back with paler grey margins, no spots on wing-coverts. 
a? Bill mostly yellow. G. adamsi, hiems, p. 11. 
b? Bill mostly black. G. immer, hiems, p. 10. 
b. A few spots on the wing-coverts. 4G. arctica, hiems, p. 11. 
Loon. Gavia immer. 
A.0.U. Checklist no 7—Colorado Records—Morrison 89, p. 147; 
Cooke 97, pp. 50, 191; Henderson 03, p. 234; 09, p. 224. 
Description.—Adult—Head and neck glossy greenish-black ; throat 
in front with two patches of white, and black streaks ; entire upper- 
parts black, spotted with white, except the upper tail-coverts and the 
primaries ; under-parts white, the sides of the breast striped with 
black ; iris red, bill and feet black. Length 34; wing 14-05; culmen 
3-0; tarsus 3-5. 
