BI RDS HIRTJNDINIDAE — HIRUNDO THALASSINA. 



311 



As a general thing specimens of this species, from the extreme south of the United States, as 

 Brownsville, Texas, and those from the western coast are considerably smaller than those from 

 Pennsylvania, 



The female is duller in color than the male ; the metallic tints of the back much more obscure 

 and less continuous. The shade is rather more violet. 



The young male of the year (164,) is entirely of a sooty grayish brown above and on the 

 wings, with the faintest possible trace of purplish reflection on the head and back. The color is 

 somewhat like that on the back of Gotyle riparia, but darker. 



It is not at all improbable that careful comparisons of many specimens may ultimately prove 

 the existence of distinct species of white-bellied swallows on the two sides of the continent. 

 The difference in size will be shown by the table of measurements. In two California specimens 

 before me, one has the same greenish gloss as Pennsylvania skins ; in the other the lustre is 

 more of a steel blue. * 



List of specimens. 



HIRUNDO THALASSINA, Swain son. 



Tiolet-Green Swallow. 



HtruTwio jAotossino, SwAiNSON, Taylor's Philos. Mag I, 1827, 365 — AuD. Orn. Biog. IV, 1838, 597; pi. 385.— 

 Ib. Birds Am. I, 1840, 186; pi. 49.— Cassin, lUust. I, 1855, 245.— Brewer, N. Am. Oology, 

 1,1857,102; pi. v, f. 74. (Egg.) 



Chelidon thalassina, Boie, Isis, 1844, 171. 



Tachydneta thalassina, Cabanis, Mus. Hein. 1850, 48. (Type.) 



Sp. Ch. — Tail acutely emarglnate. Beneath pure white. Above soft velvety green, with a very faint shade of purplish 

 violet concentrated on the nape into a transverse band. Rump rather more vivid green ; tail coverts showing a good deal of 

 purple, ^Colors of female much more obscure. 



Length, 4.75 ; wing, 4.50 ; tail, 2. 



H«6.— Rocky Mountains to Pacific ; south to Mexico ; east to Saltillo, Mexico. 



