ART. 4 BIEDS OF THE MENTAWI GROUP RILEY 6 



For an account of the physical features of Siberut and Sipora and 

 other details the reader is referred to the " Ibis " paper mentioned 



above. 



ANNOTATED LIST OF SPECIES 



TRERON CURVIROSTRA SMICRA Oberholser 



Treion curmrontra smicra Oberholser, Smiths. Misc. Coll., vol. 60, no, 7, 



1912, p. 3 (Tana Bala Island, Batu Islands). 

 Treron curvirostra Chasen and Kloss, Ibis, 1926, p. 273. 



Two males and one female, Sipora; six males and two females, 

 Siberut. 



The Sipora and Siberut birds, compared with T. c. hypothapsina 

 of Engano, have the greens above and below much more yellowish, 

 with the yellow on the greater wing coverts brighter. 



The type of Treron curvlrostra smicra of the Batu Islands is an 

 immature male not in full plumage (the describer evidently had only 

 the one specimen) ; it is brighter and more yellowish than the Engano 

 bird, but not as yellowish below as the adult males from Sipora and 

 Siberut, It approaches the female from Sipora and Siberut in color 

 of the underparts ; the head is washed with greenish, but is becoming 

 gray. It would be unsafe to separate the Sipora-Siberut birds until 

 we know what the adult of typical smicra is like. 



Treron curvlrostra pega of Nias is quite distinct, very pale below, 

 greenish glaucous, washed on the chest with light grape green with 

 a buffy tinge, and without the yellowish tinge on fchest as in smicra; 

 there are also other differences. The female is without the buffy 

 tinge on the chest, which is darker. 



Treron curvlrostra haliploa of Simalur resembles pega, but is 

 darker below and the chest is washed with grape green, without buffy 

 tinge. This form was evidently based on a single specimen. 



There thus appear to be four races of this species on the islands off 

 the west coast of Sumatra, as below : 



Treron curvirostra hypothapsina '^ from Engano. 



Treron curvirostra smicra,^ from Sipora, Siberut, and the Batu 

 Islands. 



Treron curvirostra pega ^ from Nias. 



Treron curvlrostra haliploa ^ from Simalur. 



DENDROPHASSA VERNANS MESOCHLOA Oberholser 



Dendrophassa vemans mesochloa Oberholser, Smiths, Misc. Coll., vol. 60, 



no. 7, 1912, p. 2 (Nias Island). 

 Treron vemans Chasen and Kloss, Ibis, 1926, p. 274. 



Two males, Sipora ; one male and one female, Siberut. 



' Oberholser, Smiths. Misc. Colls., vol. 60, no. 7, 1912, p, 3. 

 * Idem, p. 4. 



