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North and South America; Smerinthus (29 sp.), all regions except Australia. Our Death's Head Moth (Acherontia atropos) ranges to Sierra Leone and the Philippine Islands. General Remarks on the Distribution of the Diurnal Lepidoptera
and Sphingidea. The Diurnal Lepidoptera or Butterflies, comprehend 431 genera and 7,740 species, arranged in 16 families, according to Mr. Kirby's Catalogue published in 1871. The Sphingidea consist of 135 genera and 1,255 species, arranged in 7 families, according to the British Museum Catalogue dated 1864; and as this includes all Mr. Bates' collections in America and my own in the East, it is probable that no very large additions have since been made.
The distribution of the families and genera of Butterflies corresponds generally with that of Birds—and more especially with that of the Passerine birds-in showing a primary division of the earth into Eastern and Western, rather than into Northern and Southern lands. The Neotropical region is by far the richest and most peculiar. It possesses 15 families of butterflies, whereas the other regions have only from 8, in the Palæarctic, to 12 in the Ethiopian and Oriental regions; and as none of the Old World regions possess any peculiar families, the New World has a very clear superiority. In genera the preponderance is still greater, since the Neotropical region possesses about 200 altogether peculiar to it, out of a total of 431 genera, many of which are cosmopolitan. Comparing, now, the Eastern regions with the Western, we have two peculiar families in the former to 4 in the latter; while the Southern regions (Australian and Neotropical) possess not a single peculiar family in common.
In the Sphingidea the same general features recur in a less marked degree, the Neotropical being the richest region; but here we have one family (Castniidae) which appears to be confined to the two southern regions, the Australian and Neotropical.
The distribution of the genera affords us some facts of special interest, which must be briefly noticed. There are several
genera typically characteristic of the North Temperate regions which have a few species widely scattered on mountains, or in the temperate parts of the Southern Hemisphere. Chili possesses representatives of four of these genera— Argynnis, Lycæna, Colias, and Deilephila ; and this has been thought by some naturalists to be of such importance as to outweigh the purely Neotropical character of a large portion of the Chilian fauna, and to render it advisable to join it on, as an outlying portion of a great North Temperate zoological region. But when we remember that Argynnis occurs also in Java, and Lycona in New Zealand, while Colias ranges to Southern Africa, Malabar, aud the Sandwich Islands, we can hardly admit the argument to be a sound one.
For a fuller discussion of this question see Vol. II., pp. 43—47. The remarkable fact of the existence of the otherwise purely Neotropical genus, Urania, in Madagascar is even more striking, supported as it is by the Antillean, Solenedon, belonging to a family of Mammalia otherwise confined to Madagascar, and by one or two Coleopterous genera, to be noticed farther on as common to the two countries. Our view as to the true explanation of this and analogous phenomena will be found at Vol. I., p. 284.
The division of the Castniidæ (a family almost confined to the Tropics), between the Neotropical and Australian regions, is also a very curious and important phenomenon, because it seems to point to a more remote connection between the two countries than that indicated by the resemblance between the productions of South Temperate America with those of Australia and New Zealand; but we have already shown that the facts may be explained in another way. (See Vol. I., pp. 398 and 404).
The division of the Malay Archipelago between the Oriental and Australian regions is clearly marked in the Lepidoptera, and it is very curious that it should be so, for in this, if in any group of animals, we should expect an almost complete fusion to have been effected. Lepidoptera fly readily across wide tracts of sea, and there is absolutely no climatal difference to interfere with their free migration from island to island. Yet we find no less than 10 genera abundant in the Indo-Malayan
sub-region which never cross the narrow seas to the east of them; 6 others which only pass to Celebes; and 2 more which have extended from Java along the closely connected line of islands eastwards to Timor. On the other side, we find 5 strictly Austro-Malayan genera, and 2 others which have a single representative in Java. The following is a list of these genera :
INDO-MALAYAN GENERA Amathusia, Thaumantis, Tanacia, Eurytela, Ilerda, Zemeros, Tazila, Aphneus, Prioneris, Dercas, Clerome, Adolias, Apatura, Limenitis, Iolaus, Leptocircus, (the last six reach Celebes); Discophora, Thestias; (the last two reach Timor.)
AUSTRO-MALAYAN GENERA Hamadryas, Hypocista, Mynes, Dicallaneura, Elodina, Hyades, Prothoë (the last two reach Java).
The most characteristic groups, which range over the whole Archipelago and give it a homogeneous character, are the various genera of Danaidæ, the genus Elymnias, and Amblypodia with a few other Lycænida. These are all abundant and conspicuous groups, but they are nevertheless exceptions to the general rule of limitation to one or other of the regions. The cause of this phenomenon is probably to be found in the limitation of the larvæ of many Lepidoptera to definite species, genera, and families of plants; and we shall perhaps find, when the subject is carefully investigated, that the groups which range over the whole Archipelago feed on genera of plants which have an equally wide range, while those which are limited to one region or the otber, have foodplants belonging to genera which are similarly limited. It is known that the vegetation of the two regions differs largely in a botanical sense, although its general aspect is almost identical ; and this may be the reason why the proportion of wide-ranging genera is greater among such insects as feed upon dead wood, than among those which derive their support from the juices of the living foliage. This subject will be again discussed under the various families of Coleoptera, and it will be well to bear in mind the striking facts of generic limitation which have been here brought forward.
Fossil Butterflies, apparently of existing genera, occur in the Miocene and Eocene formations, and an extinct form in the Lower Oolite; but these cannot be held to give any adequate idea of the antiquity of so highly specialised a group, which, in all probability, dates back to Palæozoic times, since one of the Bombycidæ,—a group almost as highly-organised—has been discovered in the coal formation of Belgium. (See Vol. I. p. 168.)
GEODEPHAGA, or CARNIVOROUS GROUND BEETLES.
The Geodephaga consist of two families, Cicindelidæ and Carabidæ, differing in their form and habits no less than in their numbers and distribution. The former, comprising about 800 species, are far more abundant and varied in Tropical regions; the latter, more than ten times as numerous, are highly characteristic of the North Temperate zone, where fully half of all the known species occur.
CICINDELIDÆ. (35 Genera, 803 Species.)
The Cicindelidæ, or Tiger Beetles, are a moderately extensive group, spread over the whole globe, but much more abundant in tropical than in temperate or cold countries. More than half of the species (418) belong to the single genus Cicindela, the only one which is cosmopolitan. The other large genera are, Collyris (81 sp.), wholly Oriental ; Odontochila (57 sp.), South American, with species in Java and Celebes ; Tetracha (46 sp.), mostly South American, but with species in South Europe, North America, and Australia ; Tricondyla (31 sp.), characteristic of the Oriental region, but extending eastward to New Guinea ; Ctenostoma (26 sp.), wholly Neotropical; Dromica (24 sp.), wholly African, south of Lake Ngami and Mozambique; Therates (18 sp.), wholly Malayan, from Singapore to New Guinea.
The genera are distributed in the several regions as follows: the Nearctic region has 5 genera, 3 of which are peculiar to it; the
Palæarctic has 2, but none peculiar; the Ethiopian 13, with 11 peculiar; the Oriental 8, with 3 peculiar; the Australian 9, with 2 peculiar; and the Neotropical 15, with 10 peculiar. The connection between South America and Australia is shown by the latter country possessing 9 species of the characteristic South American genus Tetracha, as well as one of Megacephala. The small number of peculiar genera in the Oriental and Australian regions is partly owing to the circumstance that two otherwise peculiar Oriental genera have spread eastward to the Moluccas and New Guinea, a fact to be easily explained by the great facilities such creatures have for passing narrow straits, and by the almost identical physical conditions in the Malayan portion of the two regions. The insects of Indo-Malaya were better adapted to live in the Austro-Malay Islands than those of Australia itself, and the latter group of islands have thus acquired an Oriental aspect in their entomology, though not without indications of the presence of an aboriginal insect-fauna of a strictly Australian type. The relation of the Australian and Neotropical regions is exhibited by this family in an unusually distinct manner. Tetracha, a genus which ranges from Mexico to La Plata, has 9 species in Australia ; while Megacephala has 2 American and 1 Australian species. Another curious, and more obscure relation, is that between the faunas of Tropical America and Tropical Africa. This is also illustrated by the genus Megacephala, which has 4 African species as well as 2 South American; and we have also the genus Peridescia, which has 2 species in South America and 2 in Madagascar.
Several of the sub-regions are also well characterised by peculiar genera; as Amblychila and Omus confined to California and the Rocky Mountains ; Manticora, Ophryodera, Platych ile and Dromica, characteristic of South Africa; Megalomma and Pogonostoma peculiar to the Mascarene Islands; and Caledonica to the islands east of New Guinea. The extensive and elegant genus Collyris is highly characteristic of the Oriental region, over the whole of which it extends, only just passing the limits into Celebes and Timor.
The Cicindelidæ, therefore, fully conform to those divisions of VOL. II.-32