Species of the Genus Cyclorhis. 321 



In different genera of birds, as is notorious^ we find it con- 

 venient to seize upon various points o£ structure as tlie best 

 guide to their arrangement. In Cyclorhis the form and 

 colour of tlie short, compressed. Shrike-like bill appeared to 

 me to be the most salient point. In the typical species 

 allied to C. guianensis (fig. 1), and in six other nearly allied 

 forms, the bill presents a nearly uniform appearance, and 

 is further remarkable in carrying a large dark plumbeous 

 spot at the base of the lower mandible. In a seventh species 

 the bill is similar in structure, but there is no dark mark at 

 the base of the mandible. In Cyclorhis altirostris (fig. 2) 

 the structural features are carried to a greater extreme, the 

 bill being still shorter and the upper mandible still more 

 elevated. In C. nigrirostris, on the other hand (fig. 3), 

 we find a less typical kind of beak, this organ being much 

 less elevated, not so much compressed, and longer in propor- 

 tion to its size. 



I would therefore propose to arrange the ten species of 

 Cyclorhis known to me as follows : — 



A. Bill moderately thickened ; upper mandible 



about one third thicker in vertical dimen- 

 sions than the lower. 



a. Plumbeous spot at the base of the lower 



mandible. 



a'. Belly yeUow (I) flaviventi'is, p. 322. 



b\ Belly white or pale cinereous. 

 a". Breast clear yellow. 



a'". Crown greyish (2)Jlavipectus, p. 322. 



b'". Crown green, like the back : 



occiput green (3) virenticejjs, p. 322. 



occiput reddish (4) conirerasi, p. 322. 



b". Breast greenish yellow : 



I belly greyish (5) guianensis, p. 323. 



I belly white . (6) albiventris, p. 323. 



b. No plumbeous spot on mandible ; bill 



uniform reddish (7) ochrocephala, p. 323. 



B. Bill much thickened ; upper mandible 



nearly twice as thick as lower; plum- 

 beous spot on lower mandible (8) altirostris, p. 323. 



