16 TVKDIDM. 



de Chiriqui, Boqueti de Chitra, Cordillera de Tole, Calovevora, Calobre, Santa 

 Fe (Arce^ i^). 



Under the name Merula tristis Swainson, in 1827, described a Thrush from the 

 highlands of Mexico i. The description is so brief that it is hardly to be wondered at 

 that the name was for some time unrecognized or misapplied, and the same. species 

 received the new name of Turdus assimilis from Dr. Cabanis ^. As Swainson's type, still 

 existing at Cambridge, shows that the description, so far as it goes, is accurate, T. tristis 

 is certainly the right name to use for this Thrush. 



It belongs to a southern group of Thrushes, its nearest ally being T. crotopezus of 

 Bolivia and South Brazil, from which it differs but little. 



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-brown and a light-coloured tail. In Guate- 

 mala, 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 Mr. Sclater bestowed the name T. leucauchen ^^; but from the time the separa- 

 tion was made specimens have been reaching us from various parts showing characters 

 connecting by every stage of transition T. 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 T. tristis, is not nearly 

 sufficiently segregated to admit of the two races bearing distinct names. The 

 T. leucauchen form is not strictly confined to the forests of Northern Vera Paz, but is 

 found also in Honduras, Nicaragua, and Costa Eica, but everywhere mingled with birds 

 approaching the T. tristis type of colour. 



T. tristis, as we propose to call all these birds, appears to be by no means an uncom- 

 mon species in Southern Mexico, as most collectors there have obtained an abundant 

 supply of specimens. Prof. Sumichrast tells us that it has a very extended area of dis- 

 tribution in the State of Vera Cruz, being, however, restricted to the hot and temperate 

 regions below an elevation of about 4300 feet. Though a sedentary bird, he adds, it is 

 not always to be found in the same localities, but changes its residence frequently, 

 influenced by the ripening of the berries upon which it feeds ^^. M. Boucard obtained 

 its eggs in the State of Oaxaca, which Mr. Sclater described as like pale varieties of 

 T. merula, being of a pale greenish white, spotted and freckled with two shades of 

 rufous, and measuring 1-1 by 0*7 5 inch ^, 



