PASSERES. 821 
Orver PASSERES.—Percuine Birps. (Page 3) 
Families. 
a. Tarsus cylindrical, or with hinder portion rounded; encircled with a single 
horny envelope (divided into scutelle anteriorly and on outer side), this 
sometimes extending all round (though separated by a seam along inner 
side), but often widely separated on inner side or behind (or both), the 
intervening space occupied by granular scales, reticulations, or plain naked 
skin. (Suborder Clamatores.) 
b'. Inner toe with basal phalanx united to that of middle toe; posterior face of 
tarsus reticulate.......cccceccesecseccseceseeeseseeseees Cotingide. (Page 323.) 
b*. Inner toe entirely free at base from middle toe; posterior face of tarsus not 
TOtICUIALC........ccccecccsccessececcescnssseseeereseaeees Tyrannidz. (Page 326.) 
a. Tarsus compressed behind, with comparatively sharp posterior edge (or else 
hind-claw longer than its digit, and straight), the enveloping membrane 
divided into two or three longitudinal segments, which may be either divided 
into transverse segments, or scutelle, or fused into continuous plates. (Sub- 
order Oscines.) 
o'. Posterior half of tarsus not compressed, but rounded, and divided into dis- 
tinct segments, or scutelle, like the anterior half. 
Alaudidz. (Page 346.) 
- 6. Posterior half of tarsus compressed, with two lateral plates uniting behind 
in a comparatively sharp ridge, and for the most part undivided. 
c. Primaries apparently only 9 (the 10th being exceedingly rudimentary), 
the tip of the bill not hooked. 
d'. Bill variously formed, but gape never twice as long as culmen; 
outer primary never twice as long as innermost. 
e'. Bill straight. 
f*. Bill conoid ; if slender, the angle of the gonys forward of 
the nostril. 
g. Bill without notch, and without bristles at gape. 
Icteridz. (Page 365.) 
g’. Bill notched, and with bristles at gape. 
hi. Nostrils concealed by feathers, or pointed an- 
teriorly and overhung by a distinct scale 
or horny membrane, or else base of cutting- 
edges forming a distinct angle. 
Fringillide. (Page 382.) 
h?. Nostril exposed, rounded anteriorly, without 
distinct overhanging scale or membrane, and 
cutting-edges of bill not forming a distinct 
angle at the base.. Tanagride. (Page 453.) 
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