48 BIRDS OF ILLINOIS. 



d. Bill not strongly hooked. 



>. Tarsus longer than middle toe with claw, or the bill elongat- 

 ed, not depressed, narrower at base than length of culmen. 



f 1 . Bill moderately hooked at tip Vireonidae. 



/*. Bill not distinctly hooked at tip. 



o l . Tail-feathers stiff, pointed at tip Certhiidas . 



ff s . Tail-feathers normal. 



A 1 . Nasal feathers directed forward. 



i 1 . Smaller (wing less than 4.00 inches). 



j 1 . Bill notched, subulate Sylviidse (Polioptilinafi . 



3*. Bill without notch, more or less conoid Pandas. 



i> . Larger (wing more than 4.00 inches) Corridas. 



h*. Nasal feathers erect or inclined backward. 



i 1 . Bill elongate-conical, culmen straight. First 

 primary minute, not reaching to tip of coverts. 



Stnrnidse. 



t 1 . Bill not conical, culmen more or less curved. 

 First primary well developed, extending be- 

 yond tips of coverts Troglodytidse. 



. Tarsus not longer than middle toe with claw. Bill short, de- 

 pressed, width at base exceeding length of gonys 



6*. Primaries apparently only 9, the tip of the bill not hooked. 



c 1 . Bill very short, very broad at base and deeply cleft, the gape more 

 than twice as long as the culmen. Outer primary more than twice 



as long as the innermost Hirundinidee. 



c*. Bill variously formed, but gape never twice as long as eulmen, etc. 

 Outer primary less than twice as long as the innermost. 



d 1 . Bill decurved and very acute at tip Caerebidae (Certhiola). 



d*. Bill not decurved. 



e l . Bill not conoid; angle of gonys not forward of the nostril. 

 f 1 . Tertials elongated, reaching nearly to tip of longest 

 primaries. Hind claw nearly as long as, or longer 



than, its digit Motacillidae. 



6 s . Tertials not elongated, falling far short of tips of longest 



primaries. Hind claw much shorter than its digit... Mniotfltidae. 

 . Bill conoid; if slender, the angle of the gonys forward of the 



nostril. 

 /. BUI notched, and with bristles at gape. 



a 1 . Nostril exposed, rounded anteriorly, and without dis- 

 tinct operculum. Base of tomia not forming a distinct 



angle Tanagridae. 



0*. Nostril concealed by feathers, or pointed anteriorly 

 and overhung by a distinct operculum, or base of 



tomia forming a distinct angle Fringillidae 



/*. Bill without notch, and without bristles at gape Icteridae. 



a 3 . Posterior half of tarsus not compressed, but rounded and divided into dis- 

 tinct segments, or "scutellae," like the anterior half Alaudidae . 



B. Clamatores. 



a 1 . Inner toe entirely free at the bade from the middle one. Posterior face of 



tarsus not reticulate Tyrannidas. 



a*. Inner toe with basal phalanx united to that of middle toe. Posterior face 



of tarsus reticulate Cotingidse 



