54 BULLETIN OF THE NUTTALL 



third abruptly larger ; the fotirth intermediate in length between the third 

 and fifth. Entire upper parts to the tail golden-green. 



Some time since my attention was attracted by a specimen of the 

 above-described bird, in the collection of Mr. William Brewster, 

 which had been received from Mr. C. A. Allen, of Nicasio, Califor- 

 nia, the locality where it was taken. Experience in the interior, 

 especially in Arizona, had afforded opportunity for the examination 

 of hundreds of the Selasjjhorus rufiis, and this specimen, an adult 

 male, differed so decidedly from any I had ever seen that I was led 

 to the belief that there might be on the west coast a variety pecul- 

 iar to that region. The examination of specimens, however, show- 

 ing what I considered intermediate phases of coloration from this 

 same locality, led me to conclude that the form was not sufficiently 

 distinct to receive a name, an impression which I now think was 

 wholly erroneous. The reception of new material and a reconsid- 

 eration of the question has convinced me that the form in question 

 is quite distinct specifically from >S'. rufus, from which it is separable 

 by perfectly good and stable characters of external structure. As 

 might be expected in a family where the females of totally different 

 genera are often distinguishable only with difficulty, it is in the 

 males that the differences are chiefly to be noted. The narrow 

 outer tail-feathers are in the case of S. alleni sufficiently peculiar, 

 however, to enable one to distinguish the females and even the 

 young birds. 



The adult males are at once separable, not only by the bright 

 green back, the green extending partially over the upper tail-coverts 

 and contrasting sharply with the rufous of the tail, but even more 

 readily by the very peculiar characters of the tail, as above indi- 

 cated. These are perfectly constant in all the specimens I have 

 seen, and have proved to be so also in all of the many individuals 

 which have passed under Mr. Allen's notice. 



In reference to the coloi-ation of the »S'. alleni, I can state that the 

 amount of variation in the adult males is veiy small. The back is 

 always of a pure metallic green. Mr. Allen, whose authority is un- 

 questionable, and who has had ample opportunity for ascertaining, 

 writes me that the variation is extremely slight, and that a series of 

 thirty males then before him showed no differences. On the other 

 hand, I can assert with equal positiveness that the S. rvfus never 

 assumes this complete green phase of coloration. Of specimens 



