vi INTRODUCTION. 
as occur at the highest limits of the forest being very like those of similar Andean 
localities, these mostly belonging to the genera Euptychia, Archonias, Catasticta, Pereute, 
Enantia, &c.; (4) that the fauna of the Atlantic slope to perhaps as far south as 
Costa Rica is incomparably richer than that of the Pacific, this being particularly 
noticeable in the Ithomiina, the Erycinide, the genera Thecla and Papilio, &c.; and 
(5) that some of the purely tropical genera do not reach north of Nicaragua, Costa 
Rica, or Panama, as Eutresis, Scada, Cerois, Callitera, Hetera, Oressinoma, Narope, 
Panacea, Megistanis, Hypna, Zeonia, Ithomeis, &c. 
A comparison of our fauna with that of the West-Indian Islands (from which we 
exclude Trinidad and Tobago, as being Venezuelan) shows the extreme poverty of the 
latter, the Morphine being, so far as we know, wholly absent, and the Ithomiina, 
Heliconiine, Erycinide, and Brassoline having extremely few representatives *. We 
are unable to give any precise statistics as regards the total number of known South- 
American butterflies, there being no general work on the subject; but we may note 
that America north of Mexico has altogether (exclusive of giale, which in this work 
is included amongst the moths in the family Castniide) 642 species (Skinner, 1898), 
as against 1805 in our region. For the whole of the Palearctic region 716 species are 
now known (Staudinger and Rebel, 1901). Of the total number here enumerated 
from Central America, 360 are described as new. 
The distribution of the Rhopalocera enumerated in this work will be better 
understood by a few remarks on the general features of the country, the elevation of 
the land, the geological formation, &. The limits of our region are as follows :— 
the whole of Mexivo from the valleys of the Rio Grande and the Rio Gila on the 
north (Lower California thus being excluded), the five Central-American Republics of 
Guatemala, Honduras, Salvador, Nicaragua, and Costa Rica, British Honduras, and 
the Colombian State of Panama as far as the Isthmus of Darien. In Mexico we have 
the central arid tablelands, of varying extent and elevation, running from our 
northern limits southward to Guatemala and beyond, but interrupted at the Isthmus 
of Tehuantepec. The highest mountains are at no very great distance from the 
Mexican capital; south of this they become lower, till we reach the mainland of 
South America, where peaks equalling those of Mexico and much higher are again 
found. The snow-line in Central America is about 15,000 feet. Along both the 
* Lucas has recorded two species of Erycinide (Syrmatia dorylas and Charis caneus) and one of Brassoling 
(Opsiphanes cassie) from Cuba; but these statements have not been confirmed, so far as we are aware. 
