ANAS.— CHAULELASMUS. 209 
Hab, Mexico, Mazatlan (Abert®), Tepic (Grayson ?), Valley of Mexico (Herrera*), 
Guanajuato, Guadalajara (Dugés 1). 
We have not been able to examine an example -of this bird, which is also closely 
related to A. fulvigula from Florida. Mr. Ridgway says that its small size, and, to a 
certain extent, its narrow bill, recall the species of Querquedula. | 
Grayson? shot many specimens near epic, but never saw one in the vicinity of 
Mazatlan. The species doubtless breeds in the former place, as he found them there 
during the month of June in pairs. 
CHAULELASMUS. 
Chaulelasmus, Bp. Comp. List Birds Eur. & N. Amer. p. 56 (1838); Gray, List Gen. Birds, p. 74 
(1840); id. Gen. Birds, iii. p. 617 (1845); Salvad. Cat. Birds Brit. Mus. xxvii. p. 221 
(1895). 
This genus may at once be distinguished from the true Ducks by the distinct lamelle 
of the upper mandible, which project prominently over the lower. The chestnut 
wing-coverts are also a feature of the Gadwalls, and the speculum is black and white 
in both sexes, the white patch being on the inner side. ‘Ihe bill is not very broad, 
somewhat compressed, and shorter than the head. 
Two species are known—the ordinary Gadwall, C. streperus, common to the Old and 
New Worlds, and a smaller form, C. coues?, supposed to be peculiar to the Fanning 
group of islands in the Pacific. 
4 
1. Chaulelasmus streperus. 
Anas strepera, Linn. Syst. Nat. i. p. 200°; Scl. & Salv. P. Z.S. 1876, p. 382°; Ferrari-Perez, Pr. 
U. 8. Nat. Mus, ix. p. 173°; Herrera, La Nat. (2) i. pp. 187‘, 328°; Allen, Bull. Amer. 
Mus. Nat. Hist. v. p. 32°; A. O. U. Check-l. N. Amer. Birds, 2nd ed. p. 49". 
Chaulelasmus streperus, Dugés, La Nat. i. p. 142°; Lawr. Mem. Bost. Soc. Nat. Hist. ii. p. 315°; 
Baird, Brewer, & Ridgw. Water-Birds N. Amer. i. p. 506"°; Salvad. Cat. Birds Brit. Mus. 
XXVii. p. 221". 
Pileo rufescenti-brunneo, saturatiore brunneo maculato; capitis et colli lateribus ferrugineo tinctis et brunneo 
minute punctatis; collo postico sordide brunneo; interscapulio et scapularibus intimis nigricantibus, 
lineis albis vel pallide fulvis angustissimis irroratis, scapularibus externis arenario marginatis ; dorso 
postico saturate brunneo, vix albo vermiculato, uropygio supracaudalibusque velutino-nigris ; mento albido, 
gutture brunneo, nigro maculato ; preepectore albo, nigro circulariter fasciato ; pectore et abdomine albis, 
hoc imo fusco fasciato; corporis lateribus, hypochondriis et crisso albis vel fulvescentibus, fusco anguste 
fasciatis ; subcaudalibus velutino-nigris; subalaribus et axillaribus pure albis; tectricibus alarum 
minoribus brunneis, medianis castaneis; tectricibus primariorum et remigibus cinerascenti-brunneis, 
secundariis extimis albo terminatis ; secundariis medianis externe nigris, intimis externe albis, speculum 
nigrum et album formantibus; rectricibus cinerascenti-brunneis, pallidiore brunneo marginatis: rostro 
plumbeo ; pedibus sordide aurantiacis ; iride corylina. Long. tota circa 21-0, ale 11-0, caudex 4°0, culm. 1:9, 
tarsil-5. (Deser. maris adulti ex Zacatecas. Mus. nostr.) 
3 in ptilosi vera estiva femine adult similis, sed saturatior. 
¢. Supra niger, fulvo marmoratus; pileo nigro, arenario-fulvo anguste striolato; capite reliquo et collo 
BIOL. CENTR.-AMER., Aves, Vol. III., January 1902. 27 
