8 
Mr. D. G. Elliot on some 
Columbia and Bolivia respectively. Besides the great diffi¬ 
culty of recognizing more than one species by size (for there 
is absolutely no change of colour or brilliancy in the plumage 
to warrant any specific rank being granted to more than one 
form), there is the geographical distribution of the species. If 
three species are to be accepted, we find that L. splendens in 
the north is separated from L. otero in Bolivia by L. grata 
of Columbia, and that the last two become mingled toge¬ 
ther in Bolivia—not at all a probable state of things for 
really distinct species. As in many groups of Humming¬ 
birds, a variability in size of bill and length of wing, and 
perhaps also of tail, is discernible ; but if these, unsup¬ 
ported by other more important characters, are to be accepted 
as always denoting distinct species, much confusion is certain 
to be the result, and no limit can be fixed beyond which any 
naturalist, possessed with keen sight and enthusiastic appre¬ 
ciation of minute difference, may not go. It may, however, 
be advanced, with much probability, that there is only one 
species of those birds consigned to the genus Leadbeatera y 
whose range extends from Venezuela, through Columbia, into 
Bolivia, being somewhat variable in the size of the bills of indi¬ 
viduals from some localities, though it is almost certain that 
a large series of specimens would yield a regular series of in¬ 
termediate measurements. I do not see that Bonaparte had 
any reason for taking this bird out of the genus Heliodooca , 
and, therefore, have not adopted his term. 
Leucippus leucogaster. 
Trochilus leucogaster , Tschudi, Consp. Av. inWiegm. Archiv, 
1844, p. 297. 
Trochilus chionogaster , Tsch. Faun. Peruan. p. 247, t. 22. 
fig. 2. 
Leucippus chionogaster , Gould, Intr. Troch. p. 150, sp. 321. 
Trochilus (-?) hypoleucus , Gould, P. Z. S. 1846, p. 90, 
sp. 16. 
Leucippus pallidus, Tacz. P. Z. S. 1874, p. 542. 
Hab. Peru and Bolivia. 
This species, first procured by Tschudi in Peru, has received 
