430 BULLETIN 186, UNITED STATES NATIONAL MUSEUM 



The slate-colored ground thrush is known in our area only from 

 Doi Ang Ka, 4,400 feet, where two or three individuals were seen 

 by me in April, 1931; one which was collected proved to be an im- 

 mature male of the present race. 



This shy species of the dense evergreen is likely to occur in winter 

 at suitable localities throughout the northern provinces. 



The adult male has a broad and conspicuous white supercilium; 

 the rest of the upperparts and underparts slaty gray, changing to 

 white on the center of the abdomen; the remiges marked with white 

 as in the preceding species; the two central pairs of rectrices slaty 

 gray, the remaining pairs with outwardly increasingly broad white 

 tips; the under tail coverts slaty gray with broad white tips; the 

 under wing coverts and axillaries as in the preceding species. The 

 adult female has the upperparts olivaceous-brown, changing to rufes- 

 cent on the wings and tail, the upper wing coverts tipped with 

 ruf escent-buff ; a narrow buffy- white supercilium; the lores and a 

 narrow mustachial streak blackish brown; the remaining underparts 

 white (strongly suffused on the breast and upper flanks with ruf es- 

 cent-buff), the feathers tipped with dark brown but the throat, center 

 of the belly, and the under tail coverts almost immaculate; the 

 under wing coverts and axillaries as in the male but with the slaty 

 gray replaced by blackish brown. 



ZOOTHERA DIXONI (Seebohm) 



Long-tailed Plain-backed Mountain Thrush 



Geocichla dixoni Seebohm, Catalogue of the birds in the British Museum, vol. 5, 



1881, p. 161 (Nepal). 

 Oreocincla dixoni, de Schauensee, Proc. Acad. Nat. Sci. Philadelphia, 1938, p. 



30 (Doi Pha Horn Pok). 



A female, taken by de Schauensee's collectors on Doi Pha Horn Pok, 

 6,400 feet, February 10, 1938, is the sole example of this rare thrush 

 yet known from Thailand. 



It has the entire upperparts olivaceous-brown, sometimes tinged ru- 

 f escent ; the wings olivaceous-brown, most of the remiges with a buffy- 

 white area along the inner web toward the base, the upper coverts 

 with flabelliform buff tips; the two central pairs of rectrices oliva- 

 ceous-brown, the next two pairs blackish brown with very narrow white 

 tips, the fifth pair blackish brown with a broader white tip, the outer- 

 most pair olivaceous-brown (blackish brown at the base) with a broad 

 white tip and central streak; the underparts white, more or less 

 strongly washed with buff on the breast and flanks, most of the feath- 

 ers with a conspicuous semicircular black tip ; the under tail coverts 

 white, many of them edged at the sides with olivaceous-brown; the 



