Passerine Birds 259 



b* Tail-feathers normal. 



a* Bill slender, as long as the head ; tail shorter than 



the wing. Sittidae, p. 498. 



b^ Bill stoxit, shorter than the head ; tail equal to 



or longer than the wing. Paridse, p. 503. 



b^ Tarsus booted, not divided into plates except at the extreme 



base. 



a* No rictal bristles ; tail abnormally short. 



Cinclidae, p. 474. 

 b^ Rictal bristles present ; tail normal. 



a^ Small; wing under 3-0; plumage greenish; young 

 not spotted. Sylviidae (Regulus), p. 509. 



b^ Larger, wing over 3-0 ; young spotted. 



Turdidae, p. 514. 



Family TYRANNIDiE. 



Bill broad, depressed and flat, the tip down-turned ; 

 nostrils not operculate ; wings with ten primaries, the 

 outer one of which is always well developed and obvious ; 

 tail of twelve reetrices usually even or nearly so ; feet 

 small and weak, tarsus excapedian, i.e. covered with 

 variously arranged scutes, not forming a ridge at the 

 posterior edge, but meeting on the postero-internal face 

 in a deep groove. 



Six of the twelve North American genera are found 

 in Colorado. They can be distinguished as follows* : — 



A. Tips of the outer primaries attenuated ; a concealed crown- 



patch of orange. Tyrannus, p. 260. 



B. Tips of the outer primaries not attenuated ; no crown-patch. 



a. Tail marked with rufous ; a distinct crest. Myiarchus, p. 264. 



b. Tail plain coloured without rufous ; no distinct crest. 



a^ Feet very small ; tarsus not exceeding the culmen in length, 

 a* Tail very short, less than f length of wing ; a patch 

 of silky feathers on either side of the rtunp. 



Nuttallomis, p. 268. 



b^ Tail longer, about f length of wing ; no silky patch 



on rump. Myiochanes, p. 270. 



* Muscivora for/icata, the Scissors-tailed Flycatcher, is included by Cooke in the 

 Colorado avifauna on the strength of it havng been once seen by G. F. Breuninger at 

 Table Eock, on the Arkansas-Flatte divide. 



s2 



