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American species not only surpass all others in size and beauty, but some of them are so gorgeous on the under surface of their wings, as to exceed almost all the combinations of metallic tints we meet with in nature. The last family, Hesperidæ, is also wonderfully developed here, the species being excessively numerous, while some of them redeem the character of this generally sober family, by their rich and elegant coloration.
In the only other group of Lepidoptera we can here notice, the Sphingina, the Neotropical region possesses some peculiar forms. The magnificent diurnal butterfly-like moths, Urania, are the most remarkable; and they are rendered more interesting by the occurrence of a species closely resembling them in Madagascar. Another family of day-flying moths, the Castniidæ, is almost equally divided between the Neotropical and Australian regions, although the genera are more numerous in the latter. The American Castnias are large, thick-bodied insects, with a coarse scaly surface and rich dull colours; differing widely from the glossy and gaily coloured Agaristas, which are typical of the family in the East.
Coleoptera.--This is so vast a subject that, as in the case of the regions already treated, we must confine our attention to a few of the more important and best known families as representatives of the entire order.
Cicindelidæ.-- We find here examples of 15 out of the 35 genera of these insects; and 10 of these genera are peculiar. The most important are Oxychila (11 sp.), Hiresia (14 sp.), and Ctenostoma (26 sp.). Odontochila (57 sp.) is the most abundant and characteristic of all, but is not wholly peculiar, there being a species in the Malay archipelago. Tetracha, another large genus,
has species in Australia and a few in North America and Europe. The small genus Peridexia is divided between Brazil and Madagascar,-a somewhat similar distribution to that of Urania noticed above. One genus, Agrius, is confined to the southern extremity of the continent.
Carabida.-Besides a considerable number of cosmopolitan or wide-spread genera, this family is represented by more than 100 genera which are peculiar to the Neotropical region. The most important of these are Agra (150 sp.), Ardistonus (44 sp.), Schizogenius (25 sp.), Peleciun (24 sp.), Calophena (22 sp.), Aspidoglossa (21 sp.), and Lia, Camptodonotus, Stenocrepis, and Lachnophorus, with each more than 12. species. These are all tropical; but there are also a number of genera (26) peculiar to Chili and South Temperate America. The most important of these are Antarctia (29 sp.), all except two or three confined to South Temperate America ; Scelodontis (10 sp.), mostly Chilian .; Feronomorpha (6 sp.) all Chilian; and Tropidopterus (4 sp.), all Chilian. Helluomorpha (18 sp.), is confined to North and South America; Galerita, Callida, and Tetragonoderus, are large genera which are chiefly South American but with a few species scattered over the other tropical regions. Casnonia and Lebia are cosmopolite, but most abundant in South America. Pachyteles is mostly South American but with a few species in West Africa; while Lobodonotus has one species in South America and two in Africa.
Lucanidæ.—The Neotropical species of this family almost all belong to peculiar genera. Those common to other regions are Syndesus, confined to Tropical South America and Australia, and Platycerus which is Palæarctic and Nearctic, with one species in Brazil. The most remarkable genus is undoubtedly Chiasognathus, confined to Chili. These are large insects of metallic green colours, and armed with enormous serrated mandibles. The allied genera, Pholidotus and Sphenognathus, inhabit Tropical South America. Streptocerus confined to Chili, is interesting, as being allied to the. Australian Lamprima. The other genera present no remarkable features ; but Sclerognathus and Leptinoptera are the most extensive.
Cetoniidæ.---These magnificent insects are but poorly represented in America; the species being mostly of sombre colours. There are 14 genera, 12 of which are peculiar. The most extensive genus is Gymnetis, which, with its allies Cotinis and Allorhina, form a group which comprehends two-thirds of the Neotropical species of the family. The only other genera of importance are, Inca (7 sp.), remarkable for their large size, and being the only American group in which horns are developed on the head; and Trigonopeltastes (6 sp.), allied to the European Trichius. The non-peculiar genera are, Stethodesma, of which half the species are African and half tropical American; and Euphoria, confined to America both North and South.
Buprestidæ.-In this fine group the Neotropical region is tolerably rich, having examples of 39 genera, 18 of which are peculiar to it. Of these, the most extensive are Conognatha and Halecia, which have a wide range over most parts of the region; ånd Dactylozodes, confined to the south temperate zone. Of important genera which range beyond the region, Dicerca is mainly Nearctic and Palæarctic; Cinyra has a species in North America and one in Australia; Curis is divided between Chili and Australia; the Australian genus Stigmodera has a species in Chili; Polycesta has a species in Madagascar, two in the Mediterranean region, and a few in North America ; Acherusia is divided between Australia and Brazil ; Ptosima has one species in south temperate America, the rest widely scattered from North America to the Philippines ; Actenodes has a single species in North America and another in West Africa; Colobogaster has two in West Africa, one in Java and one in the Moluccas. The relations of South America and Australia as indicated by these insects has already been sufficiently noticed under the latter region.
Longicornia.--The Neotropical Longicorn Coleoptera are overwhelming in their numbers and variety, their singularity and their beauty. In the recent Catalogue of Gemminger and Harold, it is credited with 516 genera, 489 of which are peculiar to it; while it has only 5 genera in common (exclusively) with the Nearctic, and 4 (in the same way) with the Australian region. Only the more important genera can be here referred to, under the three great families into which these insects are divided.
The Prionidæ are excessively numerous, being grouped in 64 genera, more than double the number possessed by any other region; and 61 of these are peculiar. The three, common to other regions, are, Parandra and Mallodon, which are widely distributed ; and Ergates, found also in California and Europe. The most remarkable genera are, the magnificently-coloured Psalidognathus and Pyrodes; the large and strangely marked Macrodontia; and Titanus, the largest insect of the entire family.
Of the Cerambycidæ there are 233 genera, exceeding by onehalf, the number in any other region; and 225 of these are peculiar. Only 2 are common to the Neotropical and Nearctic régions exclusively, and 3 to the Neotropical and Australian. The most extensive genera are the elegant Ibidion (80 sp.); the richly-coloured Chrysoprasis (47 sp.); the prettily-marked Trachyderes (53 sp.); with Odontocera (25 sp.); Criodon (22 sp.) ; and a host of others of less extent, but often of surpassing interest and beauty. The noteworthy genera of wide range are, Oeme and Cyrtomerus, which have each a species in West Africa, and Hammatocerus, which has one in Australia.
The Lamiidæ have 219 genera, and this is the only tropical region in which they do not exceed the Cerambycidæ. This number is almost exactly the same as that of the Oriental genera, but here there are more peculiar groups, 203 against 160 in the other region. The most extensive genera are Hemilophus (80 sp.), Colobothea (70 sp.), Acanthoderes (56 sp.), Oncoderes (48 sp.), Lepturgus (40 sp.), Hypsioma (32 sp.), and Tæniotes (20 sp.). Macropus longimanus, commonly called the harlequin beetle, is one of the largest and most singularly-marked insects in the whole family. Leptostylus has a single species in New Zealand; Acanthoderes has one species in Europe, W. Africa, and Australia, respectively; Spalacopsis has a species in W. Africa; Pachypeza is common to S. America and the Philippines; Mesosa is Oriental and Palæarctic, but has one species on the Amazon; Apomecyna ranges through the tropics of the Eastern Hemisphere, but has two species in S. America ; Acanthocinus has one species in Tasmania, and the rest in South America, North America, and Europe; Phæa is wholly Neotropical, except two species in the Philippine Islands.
General Conclusions as to the Neotropical Insect-fauna.Looking at the insects of the Neotropical region as a whole, we are struck with the vast amount of specialty they present; and, considering how many causes there are which must lead to the dispersal of insects, the number of its groups which are scattered over the globe is not nearly so great as we might: expect. This points to a long period of isolation, during which the various forms of life have acted and reacted on each other, leading to such a complex yet harmoniously-balanced result as to defy the competition of the chance immigrants that from time to time must have arrived. This is quite in accordance with the very high antiquity we have shown most insect-forms to possess; and it is no doubt owing to this antiquity, that such a complete diversity of generic forms has been here brought about, without any important deviation from the great family types which prevail over the rest of the globe.
Land Shells.—The Neotropical region is probably the richest on the globe in Terrestrial Mollusca, but this is owing, not to any extreme productiveness of the equatorial parts of the continent, where almost all other forms of life are so largely developed, but to the altogether exceptional riches of the West India Islands. The most recent estimates show that the Antilles contain more species of land shells than all the rest of the region, and almost exactly as many as all continental America, north and south.
Mr. Thomas Bland, who has long studied American land shells, points out a remarkable difference in the distribution of the Operculated and Inoperculated groups, the former being predominant on the islands, the latter on the continent. The Antilles possess over 600 species of Operculata, to about 150 on the whole American continent, the genera being as 22 to 14. Of Inoperculata the Antilles have 740, the Continent 1,250, the genera being 18 and 22. The proportions of the two groups in each country are, therefore:
West India Islands.
Operculata ... Inoperculata... The extensive family of the Helicidæ is represented by 22 genera, of which 6 are peculiar. Spiraxis is confined to Central America and the Antilles ; Stenopus and Sagda are Antillean only; Orthalicus, Macroceramus, and Bulimulus have a wider range, the last two extending into the southern United