42 Proceedings of the Biological Society of Washington. 



crypta are related, and have similar habits and habitat, they differ so tren- 

 chantly in structural characters that their separation is well warranted. 



Dendrocygna bicolor helva, subsp. nov. 



Characters. — Similar to Dendrocygna bicolor bicolor (Vieillot) but lighter 

 and brighter in color on under surface; crown paler; bill smaller, narrower, 

 greatest width not more than 19.8 mm. 



Description. — Type, U. S. National Museum, Cat. No. 135588, adult 

 male, from Unlucky Lake, San Diego County, California, collected April 

 30, 1894, by Dr. E. A. Mearns. Top of head between russet and mars 

 brown, with a slight wash of dark mouse gray on posterior portion; sides 

 of head and of upper neck tawny-olive, each feather margined with buffy 

 brown, producing an appearance of faint streaks, the basic color merging 

 above with color of crown; hind-neck with a broad streak of black, bordered 

 by tawny-olive; sides of neck and foreneck lighter than pale olive-buff, the 

 feathers on the middle of foreneck and sides of neck dusky neutral gray 

 basally and laterally, producing an appearance of fine, dark, poorly defined 

 lines, arranged as a half collar; base of hind neck and upper back verona 

 brown, tipped with cinnamon-buff, feathers of upper back indistinctly 

 darker in a line marking prolongation of black neck stripe; back and wings 

 in general dull black, feathers of back and scapulars tipped broadly with 

 verona brown, changing distally to cinnamon-buflf ; lesser and middle wing- 

 coverts, save on outer portion russet, outer coverts of these two series 

 black, tipped slightly with russet; greater wing-coverts, primaries, secon- 

 daries, lower back and center of rump black; sides of rump, and lateral 

 upper tail-coverts, light buff; central upper tail-coverts nearly white; 

 rectrices dull black; throat, chin and upper foreneck dull white, washed 

 more or less with cinnamon-buff; lower foreneck and upper breast clay 

 color becoming sayal brown on lower breast, sides and abdomen, the 

 feathers tipped indistinctly with cinnamon-buff; under tail-coverts dull 

 white, washed laterally with pinkish buff; an indistinct white line through 

 center of abdomen; feathers of tibiae streaked with ivory yellow; under 

 wing-coverts and axillars blackish mouse gray; feathers of sides and flanks 

 long, streaked broadly with dull ivory yellow, the light streaks bordered 

 indistinctly with olivaceous-black. Bill, tarsus and toes dull black (from 

 dried skin) . 



Measurements (in millimeters, of type). — Wing 207.0, tail 48.3, culmen 

 44.5, tarsus 48.8, width of bill at widest point 18.1. 



Range. — Central California, western Nevada, southern Arizona and 

 central Texas south into Mexico. (Mexican specimens seen from mouth 

 of Colorado River, Lower California; San Blasito, Tepic; La Barca, Jalisco; 

 Lerma and Ixtacalco, Mexico; and Huindo, Michoacan.) 



Remarks. — The type locality of Anas bicolor Vieillot' is given as Para- 

 guay, so that the typical subspecies of the fulvous tree-duck is of South 

 American range. In the present studies we have had available six speci- 

 mens from northern Buenos Aires, Argentina that have been assumed to 



iNouv. Diet. d'Hist. Nat., Vol. V, 1816, p. 136. 



