BIRDS OF NORTH AND MIDDLE AMERICA 613 



inserted onto a transversely elongated fibrocartilaginous bar which 

 crosses the interannular membrane of bronchial semirings 1 and 2, 

 this membrane very wide owing to the fact that the first bronchial 

 semiring is much arched (the concavity being downward); while the 

 second semiring is equally arched, but with the concavity upward; 

 none of the tracheal rings are fused, and the last gives rise to a pesculus ; 

 bronchidesmus complete. 



Bill strong, its breadth at base equaling or exceeding its height at 

 same point, the culmen rounded (in transverse section) and strongly 

 decurved, the tip of the mandible strongly uncinate; gonys strongly 

 convex, prominent basally, strongly ascending and nearly straight 

 terminally, the tip of the mandible truncate; upper outhne of cere 

 continuous with that of the culmen, sometimes slightly depressed; 

 maxillary tomium with a subterminal prominent toothlike projection, 

 preceded and followed by a more-or-less-deep rounded notch, the 

 subterminal portion of mandibular tomium with a distinct notch; tip 

 of maxilla compressed, the sides of the maxilla, as viewed from above, 

 appearing swollen at the location of the tomial 'Heeth." Nostril small, 

 nearly circular, with a conspicuous central bony tubercle. Orbital 

 region bare; projecting superciliary shield conspicuous; lores with 

 bristlelike (setiform) feathers arranged more or less in a whorl. Wing 

 longer than tail, pointed, the primaries rigid, tapering to their usually 

 pointed tips, only the outermost or two outermost with inner webs 

 emarginated, the cuttings abrupt or angular and near tips of quills; 

 remiges 21-25, primaries always 10. Tail with the rectrices (12) firm, 

 more or less tapering distally, the outermost more or less bent inward 

 distally. Tibia much longer than tarsus (but less than twice as long) ; 

 tarsus usually somewhat longer than middle toe (without claw), some- 

 times twice as long, never with a single series of transverse scutella, 

 either in front or behind, often covered with small roundish scales, 

 the upper portion more or less feathered, at least in front, sometimes 

 with upper half densely feathered; outer toe (only) connected at base 

 with middle toe by an interdigital membrane; claws strongly curved, 

 acute, their under surface broadly grooved or concave. Spinal pteryla 

 starting from nape and dividing onto a long fork between the shoulders, 

 the dorsal portion commencing with two parallel rows of simple feathera 

 between the forks and becoming broader by addition of new rows 

 outside the original rows, but at the same time more sparsely feathered, 

 the two main rows uniting only at the caudal pit and then passing in 

 a broad band to the oil gland; humeral tracts not very broad, with 

 few but very large and strongly tubular feathers; lumbar tracts always 

 small, each consisting of not more than 20 feathers, sometimes almost 

 abortive, intermixed with powderdown feathers and very closely ap- 

 proximated to spinal tract; crural tracts formed of contour feathers 



