272 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



Bill rather small (exposed culnien not more than half as long as tarsus, 

 usually less), conical, its basal depth decidedly less than length of max- 

 illa from nostril and much greater than its basal width; culmen dis- 

 tinctly ridged, faintly convex throughout, or with middle portion 

 straight or even fainth' depressed; gonys very faintly convex or nearly 

 straight, much greater than basal depth of bill; maxillary tomium with- 

 out subterminal notch, nearh" straight or just appreciably concave 

 anteriorly, faintly convex posteriorly, the basal deflection very slight 

 and mostly concealed by rictal feathers; mandibular tomium straight 

 to the subbasal angle, where slightlv deflected. Nostril small, longi- 

 tudinalh^ oval, nearly concealed l)y bristly plumelets (except in ./. vul- 

 cani). Wing rather long (a little less than three to more than four 

 times as long as tarsus), moderately rounded (eighth to sixth primaries 

 longest, ninth shorter than fifth to third); primaries exceeding second- 

 aries by much less (usually about half) length of tarsus. Tail rather 

 long, usually a little shorter than wing, sometimes {J. Ixdrdi) equal to 

 wing, double-rounded, with lateral rectrices about equal to the middle 

 pair or a little longer, the rectrices rather narrow, with tips slightly nar- 

 rower and rounded or ol)tusely pointed, about half (a little more or 

 less) overlaid hy upper coverts. Tarsus moderate (a little more than 

 one-fourth to about one-third as long as tail), its scutella fairh^ distinct; 

 middle toe with claw decidedly shorter than tarsus; lateral claws not 

 reaching to base of middle claw; hallux about equal to inner toe, its 

 claw nearly or quite as long- as the digit. 



Coloration.— AdvXtii plain grayish above (back streaked only in ./. iiiil- 

 canl), but back sometimes rufescent and head sometimes black; under 

 parts plain grayish with whitish abdomen, the sides sometimes pinkish 

 or cinnamomeous, the chest and throat sometimes black; lateral tail- 

 feathers largely white (nearly or quite obsolete in J. vulcani)^ and wings 

 sometimes with two narrow Avhite bands. Sexes essentially alike. 

 Young conspicuoush' streaked both above and below. 



Range. — Boreal Province of North America, including boreal 

 "islands" south to northern Georgia, Mexico, Central America (Gua- 

 temala and Costa Rica), and Lower California. 



The only species here referred to Janco that can be considered at all 

 aberrant is J. vulcanl.^ which difl'ers from all the others in its conspicu- 

 ously streaked back, almost complete absence of white on lateral rec- 

 trices, and comparatively short wing and tail. But even including 

 J. vulcani., which is far out of place in any other recognized genus, 

 Jimco\'t^i\ much more homogeneous group than SplzMa^ or indeed than 

 most recognized genera containing an equal number of species. 



KEY TO THE SPECIES AND SUBSPECIES OF JUNCO. 



a. Head, neck, and chest without streaks. (Adults.) 



b. Back without streaks; lateral rectrices partly white; tarsus less than 25.40 mm.- 

 c. Back concolor with pileum and hindneck (gray or grayish brown) . 



