310 
ON THE CLASSIFICATION OF BIHHSi 
linaceous genera. Now this structure is carried on 
also to Polyborus, and, amid the great diversity of the 
species, in point of size and general appearance, although 
not of structure, it becomes one of its most characteristic 
marks. Polyborus is further distinguished from Ibycter 
by the curvature of the upper mandible being much 
the same as in the aberrant rapacious birds, by a much 
greater length of wing, and by the smallness of the 
external when compared with the internal claw: in 
other respects there is such a marked affinity between 
the two, that no link of the chain is wanting : the largest 
species is Polyborus vulgaris, which is equal in size to 
the goshawk. P. ochrocephalus (yfg.lOS.) is considerably 
smaller ; and an appa. 
rently undescribed spe- 
cies from Cayenne, now 
before us, is scarcely 
larger than the kes- 
trel. Hitherto no spe- 
cies of this group have 
been found beyond the 
warm latitudes of 
America; and probably 
several others are confounded among the buzzards and 
eagles. The typical species was long known to the 
older ornithologists by the name of Brazilian kite — an 
association which was founded in some truth ; for it is 
by this group and Jbycter that the kites, generally so 
called, are united to the eagles. The type, however, of 
the milvine circle, in our opinion, is the genus Cymindis 
of Cuvier, a group of birds entirely restricted to tropical 
America, and of which four species are already known. 
A very erroneous character has been assigned to Cy~ 
mindis, which is neither possessed by this genus or by 
any other in the raptorial circle with which we are ac- 
quainted : the tarsi ” have been termed semipalmated *, 
a misprint, probably, for toes ; but in either case the 
•^Cymindis — Tarsi breves semipalmati. — Zoo/o^ca/ Jourml^ vol. L 
