TURDUS TRISTIS (Swains.). 
MEXICAN WHITE-THROATED THRUSH. 
Merula tristis, Swains. Phil. Mag. 1827, p. 369. 
Turdus assimilis, Cab. Mus. Hein. Th. i. p. 4 (1850). 
Planesticus tristis, Bp. C. R. xxxviii. p. 4 (1854). 
Planesticus assimilis, Bp. C. R. xxxviii. p. 4 (1854). 
Turdus tristis, Licht. Nomencl. Av. Berol. p. 26 (1854); Salvin & Godman, Biol. Centr.-Amer., 
Aves, i. p. 15 (1879); Seebohm, Cat. Birds Brit. Mus. v. p. 211 (1881). 
Merula tristis assimilis, Chapman, Bull. Amer. Mus. x. p. 19 (1898). 
T. notæo olivascenti-brunneo, uropygio clariore: plagá gulari conspicuá albá: сапай olivaceá : rostro nigro vel 
corylino: remigibus intüs fulvo adumbratis. 
Тнів species of White-throated Thrush has generally been believed to intergrade with T. leucauchen, 
and to range from Mexico to Panama. Looking at the small series of specimens at the disposal of 
Messrs. Salvin and Godman in 1879 (cf. Biol. Centr.-Amer., Aves, i. p. 16), and Mr. Seebohm in 
1881 (Cat. Birds Brit. Mus. v. pp. 211, 212), it is scarcely to be wondered at that the former 
authors united 7. tristis and 7! leucauchen together, and that Seebohm treated them as races of one 
species. According to him, both races were to be found in Central America, and he considered that 
in Honduras, Nicaragua, and Costa Rica intermediate forms occurred. This conclusion, as will be 
seen below, I believe to be entirely erroneous. 
In the * Biologia, Messrs. Salvin and Godman write :—“ Within Mexico and Central America 
T. tristis has a wide range, extending from South Mexico to the State of Panama ; but within this 
area a very considerable amount of variation is observable in a large series of specimens. Mexican 
individuals, which are typical of T. tristis, have the back olive-hrown and a light-coloured tail In 
Guatemala, especially in the western parts, birds with a rich olive-brown back are common; but 
their tails are somewhat darker than those of Mexican specimens. Similar birds also occur at the 
extreme end of the range of the species, in the State of Panama. In the northern parts of Vera 
Paz the prevalent form of this Thrush has the back of a blackish ash-colour; the white mark on 
the throat is also more conspicuous than in the Mexican bird, and the black throat-marks more 
plainly shown. Upon one of these Vera Paz specimens Sclater bestowed the name 7. leucauchen ; 
but, from the time the separation was made, specimens have been reaching us from various parts 
showing characters connecting by every stage of transition 7. leucauchen to T. tristis. We have 
thus been obliged to merge the former name as a synonym of the latter; for it is evident that 
T. leucauchen, though in its extreme form very different from 7. tristis, is not nearly sufficiently 
segregated to admit of the two races bearing distinct names. The true 7. leucauchen form is not 
strictly confined to the forests of northern Vera Paz, but is also found in Honduras, Nicaragua, and 
Costa Rica, but everywhere mingled with birds approaching the 7. tristis type of colour.” 
Such was the conclusion arrived at by the above-named authors in 1879, and the argument 
could not have been more aptly put. 1% must, however, be remembered that at that time there was 
scarcely a specimen of these Thrushes with the date of its capture attached to it, excepting always 
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