BIRDS OF THE TRES MARIAS ISLANDS. 



Measurements of lache lawrencei and I. latirostria. 



47 



Platypsaris aglaiee insularis (Ridg.) Grayson's Becard. 



Hadrostomus aglaia- var. affinis Graysou, I'roc. Boston Soc. Nat. Hist., XIV, p. 279, 



1871; Lawr., Mem. Boston Soc. Nat. Hist., II, p. 289, 1874. 

 I'latypsaris insularis Ridgway, Man. N. Am. Birds, p. 325, 1887. 



The rose-throated becard was not common and only three specimens 

 were taken, all on Maria Madre. They were found in the heavier 

 forest on the slopes well back from the coast, and nothing unusual was 

 noted in regard to their habits. They probably occur on Maria Mag 

 dalena and perhaps on Maria Cleofa. A considerable series of speci- 

 mens from various parts of Mexico shows that a single species of rose- 

 breasted becard ranges over a large part of Mexico and has developed 

 four geographical subspecies. The ranges of these four forms may be 

 denned as follows : 



Platypsaris aglaice (Lafr.). Eastern Mexico from northern Tamau- 

 lipas south along basal slopes of the Cordillera of Vera Cruz and 

 Tabasco to arid parts of Yucatan. (Type from vicinity of Jalapa, Vera 

 Cruz.) 



Platypsaris aglaice sumiclirasti Nelson. Humid lowlands of Vera 

 Cruz, and thence southward in similar country nearly or quite to Guate- 

 mala. (Type from Otatitlau, Vera Cruz.) 



Platypsaris aglaice albiventris (Lawr.). West coast of Mexico from 

 the Isthmus of Tehauutepec to southern Arizona, ranging along river 

 valleys into the interior of western Mexico. (Type Irom Plains of 

 Colima ) 



Platypsaris aglaice insularis (Ridg.). Tres Marias Islands. (Type 

 from Maria Madre Island.) 



Typical specimens of insular is are much darker than typical examples 

 of albiventris. Specimens from the coast lowlands about San Bias are 

 intermediate in color. The island birds, however, may usually be dis- 

 tinguished by their smaller bills. Back from the coast of Tepic, 

 especially in the arid river canyons at Bolanos and near Guadalajara, 

 only typical specimens of albiventris were found. On the eastern side 

 of Mexico these two forms are paralleled by the pale bird of the foot 

 hills and adjacent interior (aglaice) and the darker one of the coast 

 lowlands (sumiehrasti). The color of extreme specimens of albiventris 

 is very different from that of aglaice and insularis, but among the series 

 from western Mexico, where albiventris has its home, are various inter- 

 mediate stages, some specimens approaching very closely to both the 



