27. CHRYSOMITRIS. 193 



above synonymy shows that most of the characters have been founded 

 on the variable shape of the bill, but the intermediate links between 

 the stoutest and the most slender-billed species are complete when 

 all are compared ; and as they appear to me to be simply modifica- 

 tions of the same style of bill, I have not separated them generi- 

 cally. 



Key to the Species. 



a. With the bead black or blackish brown. 



«'. With the throat not black [or with only a slight 

 blackish shade in C. atriceps], 

 a". Hind neck of a different colour to the crown, 

 which has always a more or less well-defined 

 black cap. 

 a'". No yellow at base of primaries ; upper tail- 

 coverts white ; inner web of tail-feathers 

 white; under surface of body bright 



yellow like the upper surface tristis, p. 195. 



'". Base of quills bright yellow, forming a more 

 or less distinct speculum. 

 a 4 . Upper tail-coverts bright golden yellow, 

 like the sides of the face and under 



surface of body yarrelli, p. 198. 



b*. Upper tail-coverts greenish, like the back, 

 with the rump a little more yellow or 

 yellowish green. 

 5 . No dull blackish shade on the throat; 

 under surface of body rather bright 

 yellow. 

 «°. Feathers below the eye and ear- 

 coverts greenish, like the sides of 



the neck spinescens, p. 199. 



6". Feathers below the eye and upper 

 part of ear-coverts black like the 



crown sclateri, p. 200. 



b'. A dull blackish shade on the throat; 

 under surface of body dull green or 



grey atriceps, p. 200. 



c 4 . Upper tail-coverts black ; crown blackish, 

 separated from the back, which is 

 blackish brown, by a yellow shade on 

 the sides of the neck, forming a half- 

 collar spinoides, p. 201. 



c'". Base of primaries white, forming a specu- 

 lum ; inner web of tail-feathers white, 

 not yellow ; upper surface green ; under , , . ^ . 



surface of body yellow Spsadma, p. A>4. 



J J | arizonce, p. 206. 



b". Entire back black, like the head and hind 

 neck. 

 a"". Inner web of tail-feathers with a white 



mark mexicana, p. 206. 



e'". No white on inner web of tail-feathers (oc- 

 casionally a small irregular white patch) colombiana, p. 208. 

 b'. Throat black. 



c". Back black, like the head ; rump also 

 black. 



VOL. III. o 



