250 TROCHILIDA. 
A few words on the classification of the Family seem necessary, as the system adopted 
differs in many points from any hitherto promulgated. So various are the characters 
possessed by the Trochilide that hardly any serve to divide the Family into large 
groups of genera; the form of the bill, the modifications of the tail, all vary to such a 
degree that they cannot be used except in a subordinate sense. A plan has been 
adopted which is no doubt somewhat artificial in its application: this takes the 
serration of the bill as a character by which to divide the whole Family into three 
sections. In some genera these serrations are very plainly visible, in others no trace 
of them can be seen, whilst in others they are very feeble and can only be traced with 
difficulty. Out of these three states three sections have been formed, dividing the 
Family into three subequal groups of genera: we do not call them Subfamilies as 
they can hardly have so high a value placed upon them. The application of this 
character brings several genera into a not unnatural proximity, and introduces a decided 
improvement in the system of arrangement. ‘Thus Hemistephania stands near Androdon, 
Thalurania not far from Chlorostilbon, Avocettula next to Lampornis. Pinarolema 
proves to belong to the same neighbourhood, and not to that of Oreotrochilus. Even 
Loddigesia is not unnaturally associated with Bellona and Cephalolepis. All these 
points are in favour of the system here adopted and seem to justify its trial. 
As the structure of the Trochilide has been very fully described in systematic works 
on ornithology, and their habits have also been recorded in the many special works on 
this favourite family, we do not propose to enter at length upon either subject here. 
We are much indebted to Mr. Ridgway for a complete list of the Mexican and 
Central-American Trochilide contained in the United States National Museum. All 
the localities he gives us not previously published are quoted in the following pages. 
TROCHILI. 
Sect. A. TROCHILI SERRIROSTRES. 
Tomia maxille ad apicem distincte serrata ; mandibula quoque eodem modo 
sepe serrata. | 
a. Rostrum cuneatum, ad basin latum, apicem versus gradatim compressum. 
HELIOTHRIX. 
Heliothriz, Boie, Isis, 1831, p. 547; Salv. Cat. Birds Brit. Mus. xvi. p. 30. 
A genus of three species, though others have been suggested. These are distributed 
over the greater part of the forest regions of Tropical America, from British Honduras 
and Eastern Guatemala to South Brazil. One species, H. darroti, occurs within our 
region and spreads southwards to Western Ecuador. 
