BIRDS OF NORTH AND MIDDLE AMERICA. 703 
b. Claw of inner toe normal (not notably larger, more stro igly curved, or sharper 
than the claws of other toes); thigh-muscle formula ABX or AX; syrinx not. 
peculiar; liver with lobes equal or the left lobe larger than the right; rectrices. 
usually 12-14 (16-18 in Cerorhinca); no fleshy rictal rosette. 
c. Mandibular rami densely covered for much the greater part with short velvety: 
feathering, the anterior edge of the feathering forming an oblique line (convex 
anteriorly) from or near the gonydeal angle to rictus; latero-frontal feathering 
also dense and velvety, advancing to or beyond anterior end of nostril and 
partly overhanging its upper margin; rectrices usually 12(14in Pinguinus only). 
(Alcine.) 
d. Bill very deep and very much compressed, transversely grooved laterally 
(in adults), the culmen very strongly curved, more or less arched; loral ° 
antia very much nearer to tomium than to culmen; tail graduated, the 
rectrices pointed. (Alcex.) 
e. Bill relatively larger and longer, the distance from anterior end of nostril 
to tip of maxilla greater than from same point to rictus; mandible with 
numerous transverse grooves (in adults); wings greatly reduced, unfitted 
for flight; rectrices 14 ..............-.2-22-0----20-- Pinguinus (p. 710). 
ee. Bill relatively smaller and shorter, the distance from anterior end of nostril 
to tip of maxilla much less than from the same point to rictus; mandible 
with notmore than two grooves; wings well-developed, fitted for pro- 
longed flight; rectrices 12.................22--.0-2--02- Alea (p. 713). 
dd.4Bill narrow, elongate-subconical, only moderately compressed, the culmen 
nearly straight for most of its length or very gently curved from about 
middle portion, without transverse grooves; loral antia about midway 
between culmen and tomium or nearer the former; tail slightly rounded, 
the rectrices not pointed. - ( Uriz.) ......-..-..-.- Lagieesee Uria (p. 717). 
cc. Mandibular rami feathered for less than greater part, the anterior edge of the 
feathering forming a more or less distinct angle or antia; latero-frontal 
feathering falling short of anterior end of nostril or else (in Synthliboramphus) 
the short and broad nasal operculum unfeathered, tarsus longer than middle 
toe without claw, and acrotarsium transversely scutellate. (Phalerinz.) 
d. Gonys much shorter than distance from its base to rictus; bill simple in form, 
small and slender, or compressed, without deciduous accessory pieces; 
latero-frontal feathering advancing to at least middle of nostril. 
. e. Bill more elongated, the latero-frontal antia much nearer to rictus than to. 
tip of maxilla, the culmen nearly straight to near tip, where abruptly 
decurved; mandibular rami mostly unfeathered, the malar antia forming 
a distinct median angle; base of culmen unfeathered to behind posterior. 
end of nostril; nostril slit-like, in extreme lower edge of the large and 
well-defined nasal fossa; size larger (wing not less than 150 mm.).. 
(COP DRE cis oars aisstrevaraccsaiiimrs siasdtimese, Fe Sieimisrecera BOraesaareiesa Cepphus (p. 732). 
ee. Bill more abbreviated, the latero-frontal or frontal antia much nearer to. 
tip of maxilla than to culmen, the latter gently to rather strongly curved 
from near base; mandibular rami mostly feathered, there being no dis-. 
tinct, if any, malar antia; base of culmen unfeathered only to slightly 
behind anterior end of nostril; nostril broadly oval, pyriform, or triangu- 
lar, near anterior end of the mostly feathered nasal fossa; size smaller- 
(wing not more than 145 mm.). ; 
f. Acrotarsium reticulate; outer toe not longer than middle toe and inner 
toe not longer than first two phalanges of middle toe; bill more slender, 
its depth at anterior end of nostril lessthan length of gonys; mandibular 
rami mostly feathered, the naked portion much shorter than gonys. 
(Brachyramphex.) 
