BIRDS OF NORTH AND MIDDLE AMERICA. 353 



prenasal groove. In A. erythrognathus Gould, from Venezuela, the 

 nostrils are still lower (at least half way from upper surface of the 

 mesorhinium to maxiUary tomium), the subnasal portion of the 

 maxilla being thus very narrow, while the bill is strongly arched, 

 the subnasal portion of the maxilla and the sides of the mandible 

 strongly concave, the nostrils narrow and concealed by the latero- 

 frontal feathering, the orbits feathered (only the loral region being 

 naked), the base of the bill without the raised, differently colored 

 margin, the mesorhinium transversly corrugated, and the rectrices 

 without the usual cinnamon-rufous or chestnut tip. A. cseruleicinctus 

 (D'Orbigny), from Bolivia, is somewhat like the last in structure of 

 the bill, but this is much less strongly arched, the subnasal portion 

 of maxilla broader, the mesorhinium not corrugated, the mandibular 

 rami relatively much shorter, and the coloration of the bill quite 

 unique in this group, being bluish horn color passing into dull 

 yellowish white terminally and along greater extent of com- 

 missure. It is also the only species (among those examined) having 

 red on the rump. 



KEY TO THE SPECIES OF AULACOEHYNCHUS. 



a. Throat and anterior portion of malar region white. 

 h. Black on basal portion of culmen broadly confluent with proximal portion of 

 black tomial area; basal embossed lamina of bill very broad and prominent; 

 forehead much paler than crown. (Southwestern Mexico.) 



Aulacorhynchus wagleri (p. 354). 

 hh. Black on basal portion of culmen widely separated from that of tomial area; 

 basal embossed lamina of bill narrow, not prominent; forehead concolor with 

 crown. (Southeastern Mexico to northern Nicaragua.) (Aulacorhynchus 

 prasinus.) 

 c. Wing and tail longer (wing 123-138, averaging 133; tail 114.5-130.5, averaging 

 121, in male); green of under parts usually more bluish, often tinged with 

 blue on chest; white of throat purer (less yellowish); chestnut of under tail- 

 coverts paler. (State of Vera Cruz, Mexico, to Guatemala.) 



Aulacorhynchus prasinus prasinus (p. 355). 

 cc. Wing and tail shorter (wing 120.5-123.5, averaging 122.1, tail 106-111, aver- 

 aging 108, in male); green of under parts more yellowish (never tinged with 

 blue); white of throat more yellowish; chestnut of under tail-coverts 

 darker. (Honduras to northern Nicaragua.) 



Aulacorhynchus prasinus virescens (p. 357). 

 aa. Throat and anterior portion of malar region deep dull blue. (Aulacorhynchus 

 cxruleogularis . ) 

 b. Prenasal portion of maxilla chestnut; slightly larger, especially the bill. (Costa 

 Rica and western Panama.) 



Aulacorhynchus cseruleogularis caeruleogularis (p. 357). 



bb. Prenasal portion of maxilla deep black; slightly smaller. (Southeastern 



Panama.) Aulacorhynchus caeruleogularis cognatus (p. 359). 



3622°— Bull. 50, pt 6—14 23 



