3. C. americanus. The gloss of the plumage purplish-violet, and hardly perceptible on head and neck, middle toe and claw rather shorter than tarsus, measured from beginning of scutellæ.
Wing, 12.25; tail, 7.20; culmen, 1.85; tarsus, 2.00; middle toe, 1.45; wing-formula, 4, 3, 5, 6, 2; first quill equal to tenth. Hab. North America generally … var. americanus.[50]
Wing, 12.50; tail, 7.20; culmen, 2.10; tarsus, 2.30; middle toe, 1.60. Wing-formula? (moulting). Hab. South Florida … var. floridanus.
4. C. ossifragus. The gloss of plumage violaceous-blue, almost green on the head, neck, and breast, where very perceptible. Middle toe and claw longer than tarsus, as above. Wing, 10.50; tail, 6.50; culmen, 1.55; tarsus, 1.65; middle toe, 1.35. Wing-formula, 4, 3, 5; first quill slightly shorter than tenth. Hab. Atlantic Coast of the United States.
b. Tarsus shorter than the bill. First quill longer than tenth.
5. C. caurinus. Gloss of the plumage as in americanus, but deeper. Wing, 10.50; tail, 6.40; culmen, 1.95; tarsus, 1.70; middle toe, 1.25. Wing-formula, 4, 3, 5. Hab. Northwestern coast of North America.
6. C. mexicanus.[51] Plumage highly lustrous, blended. Soft burnished steel-blue, changing to violet on the crown, and with a greenish cast on lower parts. Wing, 9.00; tail, 6.50; culmen, 1.60; tarsus, 1.20; middle toe, 1.10. Wing-formula, 4, 3, 5. First quill very much longer than tenth. Hab. Western Mexico (Mazatlan, etc.).
B. Angle of mouth naked—West Indian Crows.
a. Tarsus much shorter than the bill.
7. C. nasicus.[52] Nostrils scarcely concealed by the short nasal bristles. Entirely violaceous-black, the feathers smoky-gray beneath the surface. Wing, 11.00; tail, 7.75; culmen, 2.45; depth of bill, .80; tarsus, 1.95; middle toe, 1.50; graduation of tail about 1.00; wing-formula, 4, 3, 5, 6, 2; first quill shortest. Hab. Cuba.