POLYTMUS. 215 



Chrysohronchus viridtssimus, Bon., Rev. and Mag. Zool. (18.")4), p. I't'l. — (jolld, liitr. 'rrocli., octavo ud., p. 



127 (1861).— MuLs., Hist. Nat. Ois. Moucli., toiii. i, p. 27'J. 

 Clirysobronchus viridicaudus, Gol'ld, Mon. Trocli., vol. iv, pi. 2'M. 

 Chlorestes viridissimus, Keich., Troch. Eiium., p. 4, pi. 695, ligs. 45-17-48 (1655). 

 Thaumatias viridissimus, Burm., 'Jli. Bras., toiii. ii, p. 344 (1H56). 

 Thaumatias chrysurus, Burm., Th. Bras., torn, ii, p. 345 (1856). 

 Polytmus theresice, Cab. and Hbin., Mus. Heiu. Th., iii, p. 5 (1860). 



Hah. Guiana and Venezuela. 



Adult. Upper surface bronzy-green; under parts shining grass-green. Tail 

 metallic grass-green. Under tail coverts grass-green. Bill, maxilla black, mandible 

 flesh-color, tip black. Total length, 4 in. Wing, 2 1 in. Tail, 1| in. Culmcn, | in. 



Young. Beneath gray washed with green. Under tail coverts green margined 

 with white. 



3, Polytmus leucorrhous. 



Polytmus leucorrhoits, Sclat. and Salt., f. Z. S. (1867), p. 584.— Gol-ld, P. Z. S. (1871), p. 505. 

 Polytmus leucoproctus, Gray, Handl. B., pt. i, p. 128. no. 1626. 

 Chrysubronchus leucorrhous, Sclat. and Salv., Nomcncl., p. 89. 



Hah. Rio Negro, Brazil (Wallace), Rio Hnallaga, Peru (Bartlett). 



Male. Entire plumage shining green, except the head which is brown above, and 

 the under tail coverts which are pure white. Tail like C. viridissimus. Total 

 length, 3g in. AVing, 2\ in. Tail, 1^ in. Cidmen, ^ in. 



Female differs in having the outer tail feathers tipped with white. 



In the following genus, I have placed species, which, although they differ in 

 coloration, possess so far as I can perceive the same generic characters. They have 

 been divided by various authors into a number of genera, of which the chief if not 

 the only character has, in certain cases at least, been that of color. Messrs. Sclater 

 and Salvin in their Nonienclator have reduced the genera to two, Amazilia and 

 Saucerottia, but having been unable to find characters that were essentially struc- 

 tural to distinguish these, I have suppressed tlie latter also. As I have frequently 

 said in this work, color cannot be considered a generic character for Humming- 

 birds, when unsupported by any structural peculiarities, for if it is accepted in one 

 instance, to be consistent, it must be in all, and then but few species, comparatively, 

 could be passed over without being elevated to f/encric rank. The birds that are 

 now reviewed are of moderate size, certain species having a greater or less resem- 

 blance to each other in their style of coloration, and the sexes ai'e alike in plumage. 

 In numbers it is one of the most extensive genera of the Trochilida;. 



