474 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



PLATYSPIZA CRASSIROSTRIS (Gould). 

 DARWIN'S GROUND FINCH. 



Specijie characters. — Culinen strongly convex and maxillary tomium 

 strong-ly detlected from beneath nostril to rictus; gonys straight, 

 strongly ascending terminally, forming a decided angle with the lower 

 edge of the mandibular rami; mandible very broad at the base, where 

 its width greatly exceeds the length of the gonys; wing, 78.99-87.63; 

 tarsus, 26.67-29.21. 



Adult male {worn ^damage). — Head, neck, and upper chest dull 

 sooty bl'ackish, broken, more or less, by paler edgings to the feathers, 

 deepest and most uniform on upper chest and median line of throat; 

 upper parts plain brownish olive, lighter and slightly more butfy on 

 the lower rump; the general color of the wings and tail somewhat 

 darker than the back, with the margins of the feathers rather lighter, 

 especially on middle and greater wing-coverts and primaries; under 

 parts, posterior to upper chest, pale creamy yellow, shaded laterally 

 with light olive-brow^n. the lower chest and sides of breast marked 

 with broad, more or less w^edge-shapecl, streaks of sooty blackish, these 

 gradually becoming obsolete on the sides; under wing-coverts white 

 tinged with pale creamy 3'ellow, the carpo-metacarpal region with an 

 elongated space of dusky olive-grayish; bill, legs, and feet wholly black. 



Immature male. — Above olive, the pileum rather broadly and dis- 

 tinctly streaked with dusky, the feathers of the back and scapulars 

 with large central spots of a slightly darker and less olivaceous hue; 

 wings and tail as in the adult male; under parts very pale creamy 

 yellow, the whole chest and sides of breast with broad, mostly wedge- 

 shaped or sagittate spots of deep sooty brown or sepia, the sides and 

 flanks with narrower and less distinct streaks of the same; bill, legs, 

 and feet black. 



Young male. — Similar to the immature male, as described above, 

 but margins of wing-coverts more buffy, spots on chest, etc., rather 

 deeper in color, and lull light-colored (basal half of maxilla deep 

 brown, terminal half and whole of mandi])le pale butfy brownish). 



Young female. — Similar to the young male as described, but mark- 

 ings on breast, etc., less aeep (deep hair brown). 



J/«^tf.— Length (skins), about 140.00-160.00 (151.50); wing, 82.55- 

 87.63 (85.60); tail, 53.34-58.42 (56.39); culmen, 16.00-18.29 (17.53); 

 gonys, 7.37-8.13 (7.87); width of mandible at base, 9.65-10.67 (10.41); 

 depth of bill at base, 12.70-13.46 (12.95); tarsus, 27.43-28.70 (28.19); 

 middle toe, 17.78-19.05 (18.29).^ 



^ Ten specimens. 



