BIRDS OF NORTH AND MIDDLE AMERICA. 621 



Genus OPORORNIS Baird. 



Oporornis Baird, Rep. Pacific R. R. Surv., ix, 1858, 246. (Type, Sylvia agilis 

 Wilson. ) 



Medium-sized or rather small terrestrial Mniotiltidse with the tail 

 not more than two and a half times as long as tarsus, the inner webs 

 of the rectrices without white or yellow, and the under parts of the 

 l)ody (sometimes throat also) 3'ellow, the under parts without streaks. 



Bill much shorter than head, shaped quite as in Dendro/'ea, the sub- 

 terminal notch of maxillary tomiuni similarly developed. Nostrils as 

 in Dendroica. Rictal bristles weak, sometimes almost obsolete. Wing 

 long, pointed (three to four outermost primaries abruptly longest, the 

 ninth equal to or longer than sixth, sometimes equal to seventh); wing- 

 tip shorter than tarsus (nearly as long in O. agilis). Tail much sIioillu- 

 than wing (shorter than distance from bend of wing to tips of sec- 

 ondaries in O. agilis and O. forinosa^, longer in (J. 2)hiladel])liia and 

 0. tolmiei)^ slightly rounded (more decidedly so in O. i)liiladel])liia 

 and O. tolviiei), the rectrices narrowing terminally, with tips sub- 

 acuminate. Tarsus nearly one-third as long as wing (more than one- 

 third as long in O. tolmiei)., its scutella indistinct (obsolete or more or 

 less fused on outer side); middle toe, with claw, much shorter than 

 taisus; basal phalanx of middle too united for more than half (some- 

 times most of) its length to outer toe, for not more (usually less) than 

 half its length to inner toe. 



Coloration. — Above plain olive-green, becoming more or less gray 

 on pileum and hindneck in adults, or else with black on forehead and 

 crown; beneath plain yellow with throat and chest gray or gray and 

 black, or if throat also yellow a black patch on sides of head. 



JVidiJicafion. — Terrestrial. 



Range. — Temperate North America, chietly eastern; in winter south 

 through Mexico and Central America to Colombia. (Four species.) 



The two smaller species^ O. iihiJadelphia and O. tolmiei., hav ^ usu- 

 ally been placed in Geothlypix^ liut I am convinced that the}' are 

 decidedly more nearl}- related to the type species of Ojxrrornis {O. 

 agilis), their relationship to which is not only indicated by the close 

 similarity of their coloration, but also by their structure. It is true 

 they have relatively shorter wings and longer and more rounded tails 

 than O. agilix; but nevertheless they have the same pointed wing, 

 with the outermost (ninth) primary even longer (almost, sometimes 

 quite, the longest), whereas all the species of Geotldypis have the 

 ninth primary shorter than the fifth (often shorter than the fourth, 

 sometimes even shorter than the first), while in all the latter the wing- 

 tip is shorter than the exposed culmen, instead of much longer. 



O. formosa., besides differing conspicuously in the pattern of color- 

 ation of the head, neck, and chest, has the anterior toes more united 



