352 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



like basal margin (white or yellowish). Nostrils opening vertically, 

 rounded, rather small, partly covered by latero-frontal feathers, 

 widely separated by the broad, more or less arched, mesorhinium, 

 sometimes preceded by a short prenasal groove, and margined 

 beneath, or exteriorly, by a short subnasal ridge. Loral region, and 

 more or less of orbital region naked. Wing moderate or rather 

 short, the longest primaries slightly but distinctly exceeding longest 

 secondaries; fourth, fifth and sixth, or fourth and fifth primaries 

 longest, eighth slightly longer to slightly shorter than secondaries, 

 ninth a little more than two-thirds as long as longest, tenth (outer- 

 most) slightly to decidedly more than half as long as ninth. Tail 

 shorter than wing, graduated, the middle pair of rectrices longest, 

 the outer pair slightly more than half as long; the rectrices tapering 

 terminally, with tip narrowly rounded. Tarsus decidedly longer 

 than middle toe with claw. 



Coloration. — General color uniform green, the pileum and hindneck 

 more olivaceous, the chin and throat white, grayish, or blue; under 

 tail-coverts and broad tips to rectrices cinnamon-rufous or chestnut. 

 (Sexes alike.) 



Mange. — Southern Mexico to Peru, Bolivia, and British Guiana. 

 (Fifteen species.) 



The above description of generic characters is taken from two 

 of the three Central American species and two Colombian species, 

 A. alhivittus (Boissoneau) and A. Jixmatopygius Gould, that may 

 be considered as truly congeneric. The type of the genus A. sulcatus 

 (Swainson), I have not seen, but judging from the specific name I 

 suspect that it may be related to one or another of the South American 

 species which I have, for the present at least, excluded as being prob- 

 ably not congeneric with the Central American species. Unfortu- 

 nately I have been able to examine only seven of the fifteen recognized 

 species, and, therefore, am not able to decide at the present time 

 whether the genus, as generally understood, should be subdivided 

 or not. Certainly three extralimital species which I have been able 

 to examine are very different in the structure of the bill, not only 

 from the Central American species and A. alhivittus but, to a greater 

 or less extent, from one another. The one coming nearest to the 

 latter is A. derbianus Gould, from Ecuador, Peru, and Bolivia; but 

 this differs decidedly in having the nostrils situated much lower 

 (about one-fourth the distance from the upper surface of the mes- 

 orhinium to the maxillary tomium) and preceded by a very distinct 

 prenasal sulcus which extends for more than the basal half of the 

 maxilla, the culmen being very broad and flat, with distinct lateral 

 edges from which the sides of the maxilla drop vertically to the 



