52 BULLETIN 117, UNITED STATES NATIONAL MUSEUM. 



been my predecessors. It is evident, however, from the material 

 at hand, that there are two well-marked forms, a light and a dark. 

 The dark form appears to be the only one found in Chile, v/here it 

 ranges from the Straits of Magellan region northward. The light 

 form appears to be the only one found east of the Andes, where it 

 ranges from the Falkland Islands north, at least, to northern Argen- 

 tina, Thus far the case seems clear, but when we reach the Andean 

 table-land it is complicated by the occurrence of both forms, and 

 what appears to be intergrades between them, from at least the 

 vicinity of Cochabamba, Bolivia, to Lake Junin, Peru. 



This intergradation is not a gradual merging of one form into 

 another, since typical specimens of both dark and light forms were 

 secured at the same place, within two days of each other, as appears 

 from the appended consideration of table-land specim.ens. 



Bolivia. — Vinto, 8,600 feet, Province Cochabamba. An unsexed, 

 immature specimen taken July 7, streaked above and below, repre- 

 sents the dark form and resembles in size and color a bird of the same 

 age from Ancud, Chile. The ground color below is ochraceous 

 broadly streaked with black; the upper parts are blackish streaked 

 with ochraceous. 



Peru. — Puno, Lake Titicaca. A fully adult male with long 

 nuptial plumes and enlarged sexual organs, taken Jui}^ 26, is inter- 

 mediate between cyanocepJiahis and naevius in color, but agrees 

 with the former in size. (Wing, 319 mm.). It agrees very nearly 

 with a male in similar stage of plumage from the Falkland Islands. 

 An immature female, taken August 26, is typical of the light form 

 and agrees in color and size with a specimen from Tafi del Valle, 

 Province Tucuman, Argentina. 



La Raya, 14,000 feet (about midway between Puno and Cuzco). 

 A nearly adult male taken x4.pril 10, in much worn plumage and 

 undergoing a complete molt into adult plumage, can be matched by 

 specimens from Jujuy, Argentina, which are but slightly darker than 

 average examples of 7iaevius from the United States. An adult 

 male in fuU molt, taken April 8, at La Raya, is fairly typical of the 

 dark form, and agrees essentially in color and in size v/ith a bird of 

 the same age from Temuco, Chile. Consequently we have from 

 La Raya, taken within two days of each other, fairly typical speci- 

 mens of tayazu-guira and cyanoceplialus. 



A nearly adult female in fuU molt, taken April 22 at Calca, in the 

 Cuzco region, is typical of the light form and agrees with the La 

 Raya female just mentioned. A young m.ale taken March 13, at 

 Junin is typical of the light form, while and adult male taken on the 

 same day at the same place is intermediate between the light and 

 dark forms. It is slightly darker than the intermediate specimen 



