454 BULLETIN 50^ UNITED STATES NATIONAL MUSEUM. 



than half as long as the next and mostly concealed by the under tail- 

 coverts. Tarsus decidedly longer than middle toe with claw, 

 decidedly to very slightly shorter than distance from nostril to tip 

 of maxilla. 



Coloration. — Prevailing color plain green or olive-green, more bluish 

 on terminal portion of tail and on primaries, the under parts some- 

 times more rufescent; pileum bright blue (with or without a black 

 central spot and external cincture) or (together with hindneck) 

 wholly rufescent; auricular tuft and narrow jugular tuft black, some- 

 times edges with blue. 



Range. — ^Mexico to eastern Peru, Bolivia, south-central Brazil, 

 Cayenne, Trinidad, and Tobago. (About seventeen species and sub- 

 species.) 



KEY TO THE SPECIES AND SUBSPECIES OF MOMOTUS.O 



a. Pileum blue (at least exteriorly). 

 6. Pileum wholly blue of greenish blue (-without any black central area). (North- 

 eastern Mexico.) Momotus ccaruliceps (p. 455). 



bb. Pileum with a central area of black. 

 c. Feathers of posterior margin of blue crown-ring tipped with black, forming a 

 more or less distinct black border, the feathers beneath this without admix- 

 ture of cinnamon-rufous or tawny; posterior under parts greenish; larger 

 (wing 122-151, averaging more than 130). {Momotus lessonii.) 

 d. Larger (averaging wing more than 135, tail more than 220, culmen more 

 than 40). 

 e. Smaller and more tawny below; wing averaging 139.5 in male, 135.1 in 

 female; tail 230.5 in male, 220.7 in female; culmen 43.1 in male, 40.9 

 in female. (State of Chiapas, southern Mexico to western Panama.) 



Momotus lessonii lessonii (p. 457). 



ee. Lai^er and with under parts more greenish; wing averaging 142.8 in male, 



137.5 in female; tail 235.3 in male, 224.1 in female; culmen 43.1 in 



male, 42.7 in female. (States of Vera Cruz, Oaxaca, and Tabasco, 



southeastern Mexico.) Momotus lessonii goldmani (p. 460). 



dd. Smaller (wing averaging 129.6 in male, 129.7 in female; tail 215.1 in male, 

 207.3 in female; culmen 39.2 in male, 38.7 in female). (Yucatan and 



Campeche.) Momotus lessonii exiguus (p. 460). 



cc. Feathers of posterior margin of pileum not tipped with black, the feathers 

 beneath the blue occipital crescent more or less intermixed or suffused with 

 cinnamon-rufous or tawny; posterior under parts rufescent. {Momotus 

 subrufescens .) 



o With the very satisfactory material that has been brought together in connection 

 with the present work the temptation is very great to present a key to all the forms of 

 this genus, since the South American ones are in a state of almost chaotic confusion. 

 There seem to be several South American species, each having two or more sub- 

 species or geographic representative forms the distribution and relationship of which 

 is very imperfectly understood. But lack of time renders it necessary that the task 

 of working out the problems connected with the extralimital forms be left for some 

 one who has the leisure to do so. 



