, NATURAL SCIENCES OP PHILADELPHIA. 73 



under parts as far as the abdomen have a rufescent hue. There is, as yet, no 

 trace of the recurving and serration of the outer web of the first primary. 



It is quite possible Uat these specimens should be referred to Dr. Sclater's 

 Colyle fuloipennis, from Mexico. 



LAmiDM. 



113. Collyrio bokealis (Vieill.) Baird. 



Rare winter resident. A single specimen, taken in February. Iris brown ; 

 mouth yellowish white ; bill black, except at base of lower mandible ; feet 

 black. 



This is about the southernmost locality whence the species has thus far 

 been recorded. 



114. Collyrio excubitoroides (Sw.) Baird. 



Rare. Single and only specimen taken September 4th, 1864. The species 

 is probably resident in this locality, though far from abundant. 



VIREONIDJE. 



115. Vireo Swainsoni Baird. 



V. Swainsoni, Baird, B. N. A., 1858, p. 336; in text under V. gilvus ; 

 name suggested, if western species be distinct. Coues, Newton's 

 Ibis, April, 1865, p. 164. 

 V. gilvus, Cooper and Suckley, Nat. Hist, of Washington Territory, 1860, 

 p. 188. 



Sp. Ch. Size and general aspect of V. gilvus. Upper parts olive ash, 

 decidedly less olivaceous than in gilvus ; so that the back is nearly concolor 

 with the head. Below whitish scarcely appreciably washed with yellowish, 

 and only along the sides ; the median portions of the under parts pure white. 

 Other markings less distinctly defined than in gilvus. Wing more rounded : 

 fourth primary longest ; third and fifth equal to each other and nearly as 

 long; second much shorter than the sixth; hardly exceeding the seventh. 

 First (spurious) primary decidedly longer than in gilvus (-10 to -15 of an 

 inch.) 



Habitat. Rocky Mountains to the Pacific. Common summer resident at 

 Fort Whipple, arriving in April and remaining until October. 



Comparisons. All the very numerous specimens of Vireo " gilvus " from the 

 Pacific slope of the Rocky Mountains constantly differ from the eastern type 

 by the quite appreciable characters expressed in the preceding diagnosis. 

 These differences, though slight indeed, are quite tangible, and, in a group 

 so little liable to variation as the Vireones, are very probably indicative of 

 specific distinction. 



The most notable distinction is found in the proportionate lengths of the 

 primaries. All eastern gilvus that I have seen have the third quill longest, 

 or the third, fourth and fifth about equal and longest, the second being equal 

 to or longer than the sixth. In the present bird the fourth quill is decidedly 

 longest; the third and fifth successively a little shorter, while the second is 

 about equal to or but little longer than the seventh, never equalling the sixth. 

 The spurious primary is from one to nearly two-tenths of an inch longer 

 than in gilvus. In addition there is a decidedly ashy rather than olivaceous 

 wash on the upper parts, rendering the crown and back nearly concolor; and 

 there is less sulphury yellow on the under parts. 



Whether these differences be "specific" or not it is certainly well to define 

 them, and give to the species or race a name by which it may be recognized. 

 Prof. Baird first called attention to these discrepancies, suggesting the name 

 I have adopted in thus characterizing the new species. 



In the discrepancies in the proportionate lengths of the quills of this 

 Species and V. gilvus, there is discernible a striking analogy with the dis- 

 tinctive characters of Carpodacus californicus as compared with C. purpureus. 



1866.] 



