BIRDS OF NORTH AND MIDDLE AMERICA. 595 



slightly notched near tip, and ver}^ abruptly deflected basally, from im- 

 mediately beneath the nostril; the mandibular tomium slightly sinuated 

 in front of the prominent rounded subbasal angle, slightly convex 

 toward the acute ''ip of the mandible, the basal deflection very great. 



In C. cyanea the bill is relatively nearly as large as in G. concreta, 

 but the culmen is decidedly convex and distinctly ridged; the maxillary 

 tomium is much less "lobed" or convex in the middle portion and less 

 abruptly deflected basally ; the mandibular tomium is strongly convex, 

 with the subbasal angle much less evident and relativelj^ farther for- 

 ward, the tomium having thus a stronglj- arched general outline, 

 while the width of the mandible is decidedly greater than that of the 

 maxilla. 



C. parellina and its allies, O. p. indigotica and O. p. sundchrasti, 

 while agreeing with O. cyanea in the form of the bill, has this member 

 relatively much smaller, the culmen being not more than five-eighths 

 as long as the tarsus, and the tail, instead of being decidedly rounded, 

 is very little so or sometimes almost even. 



It is vei'y difficult, with the material before me, to decide what are 

 distinct species and what merely geographic races among the forms 

 usually recognized. Nothing can be more obvious, however, than 

 that C. concreta and the more southern form usually called Guiraoa 

 cyanoides (not the Coccoborus cyanoides of Lafresnaye, however) com- 

 pleteh" intergrade, and are therefore merel}' subspecies. The true O. 

 cyanoides seems to be a distinct species, and although generallj^ con- 

 founded with C. cyaiiea is far less related to that species than to the 

 southern form of C. concreta before mentioned. There are evidently 

 two or more subspecies of O. cyanea, one of which has been separated 

 by Dr. Sharpe. 



KEY TO THE SPECIES AND SUBSPECIES OF CYANOCOMPSA. 



a. Bill much larger (culmen, from base, 18.03 or more, depth of bill at base more 

 than 12.70); tail decidedly rounded. 

 b. Plumage blue. (Adult males. ) 

 c. Bill larger (.culmen, from base, 19.81-22.61) ; color duller blue (blackish blue 

 or dull indigo, brighter on forehead and lesser wing-coverts but not on 

 malar region) . ( Cyanocompsa concreta. ) 

 d. Dull blackish blue, becoming dull indigo blue on forehead and lesser wing- 

 coverts. (Southern Mexico to Nicaragua.) 



Cyanocompsa concreta concreta, adult male ( p. 596) 

 dd. Dull indigo blue, becoming dull cerulean blue on forehead and lesser 

 wing-coverts. (Southeastern Honduras to western Ecuador.) 



Cyanocompsa concreta cyanescens, adult male (p. 597) 



cc. Bill smaller (culmen, from base, 18.03-18.54) ; color brighter blue (bright 



indigo) , becoming clear azure blue on forehead, malar region, and lesser 



wing-coverts. (Lower Amazon Valley to British Guiana; Isthmus of 



Panama?) Cyanocompsa cyanoides, adult male (p. 599) 



bb. Plumage brown. (Adult feroa'es and j'oung.) 

 c. Bill larger (culmen, from ba^^e, 19.81-23.37) ; color more rusty brown. 



