OF THE AMAZON VALLEY. 
499 
Gallinacea (Penelopidce and Cracida), and other groups of the same region, point to 
the gradual adaptation of the fauna, during an immense lapse of time, to a forest-clad 
country. 
I found on the banks of the Amazons 94 species (besides many local varieties, con- 
sidered by some authors as species) of the two groups (67 Danaoid and 27 Acraeoid), 
representing all the genera of the family but three. They are most numerous in those 
parts of the country where the forests are most extensive and the climate most sultry and 
humid. I found the number of species to increase in travelling from east to west, from the 
Lower Amazons towards the eastern slopes of the Andes. They were rare in 1 1 le somewhat 
drier tract of country which borders the Lower Amazons about the middle of its course. 
I found in this large district only 26 species, namely, 10 belonging to the Danaoid and 
16 to the Acrseoid group. "Within an area of about the same dimensions, in the moist 
region of the Upper Amazons, I collected 64 species, of which 42 were Danaoid and 
22 Acrseoid Heliconidce. I should judge, from the collections received in England 
from those parts, that the hot Andean valleys near Bogota, or in Ecuador, contain a 
still larger number of species than the plains of the Upper Amazons. In the dry forests 
which clothe a great part of the banks of the Tapajos I found exceedingly few : at one 
locality, where I collected four months, and which was rich in other families of Lepi- 
doptera, I saw only one species of the Danaoid and four of the Acrseoid group. Accord- 
ing to Dyson, many species (Ithomice) of the lowlands in Venezuela have a vertical range 
of 2000 feet, and some genera (Hymenitis [H. Dercetis], Oh/ras, Eutrcsis), which do not 
inhabit the Amazon region, occur at an elevation of 8000 feet. The species are exceed- 
ingly abundant in individuals wherever they occur : they show every sign of flourishing 
existence, although of slow flight, feeble structure, unfurnished with apparent means of 
defence, and living in places which are incessantly haunted by swarms of insectivorous 
birds. The pathways in the forest near towns are quite enlivened by the multitudes 
which fly about amongst the lower trees, in their bright dresses of orange, blue, and 
yellow, and red and black. 
The mode of flight of the members of the two groups is somewhat different. The 
Heliconii and Eueides move along in a sailing manner, often circling round for a con- 
siderable time, with their wings horizontally extended. The species of the Danaoid 
group, for the most part, keep near the ground, and have a very slow irregular flight, 
settling frequently. They are all of social or gregarious habits. Not only do individuals 
of the same species congregate in masses, but the set of closely allied species which people 
a district keep together in one or more compact flocks. I noticed in four districts rich in 
Danaoid Heliconidce, where I collected, that about half the species of Ithom ia flew 
together in one circumscribed area of the forest, and the other half in a second similar 
locality, the rest of the tolerably uniform wooded country, in each case, being nearly 
untenanted by them. The larger species (Heliconii, Lycorece) frequent flowers, probing 
the nectaries with their proboscides; but the smaller kinds (Ithomia), and the members 
of the Danaoid group generally, are very rarely found thus occupied : I noticed them 
sometimes imbibing drops of moisture from leaves and twigs. The fine showy Heliconii 
often assemble in small" parties, or by twos and threes, apparently to sport together or 
