Calamospiza. Bill moderate, the commissure with a deep angle posteriorly and prominent lobe behind it; anteriorly nearly straight; commissure of lower mandible with a prominent angle. Outer toe longer than the inner, both nearly as long as the posterior. Outer four primaries about equal, and abruptly longer than the rest. Tertials nearly equal to primaries. Tail-feathers broad at tips. Color: black with white spot on wing in ♂, brownish streaks in ♀. Nest on or near ground; eggs plain pale blue.
Euspiza. Bill weaker, the commissure with a more shallow angle, and much less prominent sinuation behind it; anteriorly distinctly sinuated. Outer toe shorter than inner, both much shorter than the posterior one. First primary longest, the rest successively shorter. Tertials but little longer than secondaries. Tail-feathers attenuated at tips. Color: back brown streaked with black; throat white; jugulum yellow or ashy; with or without black spot on fore neck. A yellow or white superciliary stripe. Nest on or near ground; eggs plain pale blue.
b. Feet weaker, scarcely reaching beyond lower tail-coverts; species arboreal.
a. Size large (wing more than 3.50 inches).
Hedymeles. Upper mandible much swollen laterally. Colors: no blue; upper parts conspicuously different from the lower. Wings and tail with white patches; axillars and lining of wing yellow or red. Female streaked. Nest in a tree or bush; eggs greenish, thickly spotted.
Guiraca. Upper mandible flat laterally. Colors: ♂ deep blue, with two rufous bands on wings; no white patches on wings or tail; axillars and lining of wing blue; ♀ olive-brown without streaks. Nest in a bush; eggs plain bluish-white.
b. Size very small (wing less than 3.00 inches).
Cyanospiza. Similar in form to Guiraca, but culmen more curved, mandible more shallow, the angle and sinuations of the commissure less conspicuous. Color: ♂ more or less blue, without any bands on wing (except in C. amæna in which they are white); ♀ olive-brown. Nest in a bush; eggs plain bluish-white (except in C. ciris, in which they have reddish spots).
B. Wing and tail about equal. The smallest of American Conirostres. Nest in bushes. Eggs white, spotted.
Spermophila. Bill very short and broad, scarcely longer than high, not compressed; culmen greatly curved. Color: chiefly black and white, or brown and gray.