FAMILY TI1RAUPIDAE 



395 



This species inhabits woodland borders and clearings with scattered 

 trees and is usually found in small groups. I have seen them most 

 often feeding on mistletoe berries. This diet is correlated with an aber- 

 rant form of the stomach (Wetmore, Auk, 1914, pp. 458-461). All 

 euphonias that have been examined have a large, well-developed glan- 

 dular proventriculus, while the stomach proper is indicated by a thin 

 transparent membranous band or zone which passes over, without les- 

 sening in size, into the dilated end of the small intestine, lined internally 

 with projecting villi. As mistletoe berries are readily assimilated and 

 the process of digestion apparently is carried out entirely by secretions 

 of the alimentary canal, the ventriculus has degenerated into a thin 

 band and the stomach has straightened to facilitate the passage of food. 



Ridgely (1976, p. 374) says this species is "rather quiet, but some- 

 times gives a single high chup, a little reminiscent of a House Sparrow." 

 Slud (Bull. Am. Mus. Nat. Hist., 128, 1964, p. 345) describes several 

 other notes, including a tsoor and a tsyip. 



A nest and eggs of this tanager was collected by Monniche on the 

 Volcan de Chiriqui on May 13, 1932, (Blake, Condor, 1956, p. 388). 

 The nest was 5 m from the ground in the crown of a small tree and was 

 a compact cup made of moss with a few dried leaves and plant stalks, 

 and lined with fine black rootlets. Outside dimensions were 14x 1 1.5 X 

 7.6 cm;' the interior was 6.4x9.5 cm. The two eggs measured 23 .4 X 

 17.3 and 23 X 18 mm; they were creamy white, thickly dotted with fine 

 spots of very dark purplish brown and dull chestnut. 



Ridgely (in lift.) found a pair of this species building a nest on the 

 grounds of the Dos Rios Hotel outside Volcan on March 6, 1976. The 

 nest was in a tree fork about 18 m above the ground. In material, it 

 was like the one described above. Both members of the pair rapidly 

 brought in material (Usnea-type mosses), and often worked together, 

 though the female always preceded the male in flying to the nest. 



EUPHONIA XANTHOGASTER ORESSINOMA Olson: Orange-bellied 

 Euphonia, Tanagra Ventrinaranja 



EupJionia xanthogastcr oressinoma Olson, 1981, Proc. Biol. Soc. Wash., 94(1), 

 p. 102. (Hacienda Sofia, Rio Samana, Caldas, Colombia.) 



Very small; male, glossy dark blue on upper surface and throat, with 

 bright yellow crown and yellow breast and belly; female, dull yellowish 

 green on upper surface, sides, and flanks; buffy gray on central under- 

 surface. 



Description. — Length 95-102 mm. Adult male, fore- and mid-crown 



