498 MR. H. W. BATES ON THE LEPIDOPTERA 
There is a very wide dissimilarity in minor points and in general appearance between 
the Asiatic set of forms and the American : the only Old World genus which at all 
approaches the New World group is Hamadryas ; but the shape, colours, and neuration 
of the wings show that it has no close affinity with them. The two sets of forms seem 
to agree, however, in habits, and apparently occupy the same sphere in the economy of 
nature in their respective countries. Mr. Wallace, who has had the good fortune to 
observe both in their native abodes, says, the habits of the .South Asian Euplosce (the 
most numerous genus) are precisely those of the Heliconida . The Asiatic Danaida are 
mostly above the middle size, and include some of the largest Butterflies known ; then- 
American equivalents are in general below the middle size. Both are extremely prolific 
or abundant in individuals, and are amongst the most characteristic productions of then- 
respective countries. Each set, also, are the objects of numerous mimetic resemblances 
on the part of other Lepidopterous insects of their own region belonging to different 
families,— the Asiatic mimickers being modelled after the Asiatic Danaidce, and the 
American after the American members of the same family. The entire dissimilarity of 
the two sets of forms would seem to teach us that there can have been no land com- 
munication east and west between the tropical parts of Asia and America since they first 
came into existence, and therefore that the great continents must have remained separate 
in those quarters from a very remote epoch to allow for such an extensive independent 
development of forms. They are both strictly confined to the hottest parts of their 
respective hemispheres. In America they are not found beyond the northern tropic, 
nor much farther south than 30° S. lat. They are not known to occur so far from the 
equator as either tropic in the Old World, but are limited to the south-eastern parts of 
Asia and the islands of the New Guinea group. The genus Dcmais, with which we have 
seen both groups are connected, ranges as far north as 41° in Europe, and 45° in North 
America. It is interesting thus to find that the only genus which is common to the 
three tropical regions is the sole one of the family that occurs in high latitudes. The 
only means of communication between the intertropical lands of America and Asia seems 
to have been a circuitous route by the north (or south) ; and the essentially tropical 
forms do not appear to have passed along it. The fact of the peculiar equatorial Asiatic 
Danaid<z not reaching Africa is explicable on the same grounds as their entire distinct- 
ness from the American ones, namely, the non-existence of an equatorial connexion of 
land of a nature suitable for their transit between the two continents since the remote 
date when the first forms of the group came into being. 
The habits of the Heliconida have been described by various travellers,— Lacordaire 
having given a complete account of the Cayenne species, and Dyson and Gosse some 
interesting notes on those of Venezuela and Jamaica. The total number of species de- 
scribed is 284, namely, 233 belonging to the Danaoid, and 51 to the Acraaoid group. They 
peculiarly creatures of the forests, and, like the Platyrrhine Monkeys, the arboreal 
stomoses with the median a short distance from its origin. In the systematic part of the present memoir I shall 
• oilow Dr. Felder in this altered classification. The two groups which composed the family Heliconida are, it must be 
repeated, completely and widely distinct. Yet the analogical resemblance between them is so great, that some species 
ot the one might easily be confounded (if not closely examined) with species of the other. 
