# The Geographical Distribution of Animals/Chapter 21

CHAPTER XXI.
THE DISTRIBUTION OF SOME OF THE MORE IMPORTANT FAMILIES AND GENERA OF INSECTS.
Although insects are, for the most part, truly terrestrial animals, and illustrate in a very striking manner the characteristic phenomena of distribution, it is impossible here to treat of them in much detail. This arises chiefly from their excessive numbers, but also from the minuteness and obscurity of many of the groups, and our imperfect knowledge of all but the European species. The number of described species of insects is uncertain, as no complete enumeration of them has ever been made; but it probably exceeds 100,000, and these may belong to somewhere about 10,000 genera—many times more than all vertebrate animals together. Of the eight Orders into which Insects are usually divided, only two—the Coleoptera and Lepidoptera—have been so thoroughly collected in all parts of the globe that they can be used, with any safety, to compare their distribution with that of vertebrate animals; and even of these it is only certain favourite groups which have been so collected. Among Lepidoptera, for example, although the extensive group of Butterflies may be said, in a general sense, to be thoroughly well known—every spot visited by civilized man having furnished its quota to our collections—yet the minute Tineidæ, or even the larger but obscure Noctuidæ, have scarcely been collected at all in tropical countries, and any attempt to study their geographical distribution would certainly lead to erroneous results. The same thing occurs, though perhaps in a less degree, among the Coleoptera. While the Carabidæ, Buprestidæ, and ​Longicorns of the Tropics, are almost as well known as those of the Temperate Zones, the Staphylinidæ, the smaller Elateridæ, and many other obscure and minute groups, are very imperfectly represented from extra-European countries. I therefore propose to examine with some care the distribution of the Butterflies, and the Sphingina among Lepidoptera, and the following large and well-known families of Coleoptera:—Cicindelidæ, Carabidæ, Lucanidæ, Cetoniidæ, Buprestidæ, and the three families of Longicorns. These families together contain over 30,000 species, classed in nearly 3,000 genera, and comprise a large proportion of the best known and most carefully studied groups. We may therefore consider, that a detailed examination of their distribution will lead us to results which cannot be invalidated by any number of isolated facts drawn from the less known members of the class.
Range of Insects in Time.—In considering how much weight is to be given to facts in insect distribution, and what interpretation is to be put upon the anomalies or exceptional cases that may be met with, it is important to have some idea of the antiquity of the existing groups, and of the rate at which the forms of insect life have undergone modification. The geological record, if imperfect in the case of the higher animals, is fragmentary in the extreme as regards indications of former insect life; yet the positive facts that it does disclose are of great interest, and have an important bearing on our subject. These facts and the conclusions they lead to have been discussed in our first volume (p. 166), and they must be carefully weighed in all cases of apparent conflict or incongruity between the distribution of insects and that of the higher animals.
Order—LEPIDOPTERA.
Sub-order—Lepidoptera Rhopalocera, or Butterflies.
Family 1.—DANAIDÆ. (24 Genera, 530 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| 1. 2. 3. 4 | 1. 2. 3. 4 | — 2 — — | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 |
The Danaidæ are now held to comprehend, not only the whole of the group so named by Doubleday, but a large portion of the Heliconidæ of that author. Their range is thus extended over the whole of the tropical regions. A few species spread northwards into the Palæarctic and Nearctic regions, but these are only stragglers, and hardly diminish the exclusively tropical character of the group. The more remarkable genera are,—Hestia (10 sp.), and Ideopsis (6 sp.), confined to the Malayan and Moluccan districts; Danais (50 sp.), which has the range of the whole family; Euplœa (140 sp.), confined to the Oriental and Australian regions, but especially abundant in the Malayan and Moluccan districts; Hamadryas (4 sp.), Australian region only. The remaining genera constitute the Danaioid Heliconidæ, and are strictly confined to Tropical America, except a few species which extend into the southern parts of the Nearctic region. The chief of these genera are:—
Ithomia (160 sp.), Melinæa (18 sp.), Napeogenes (20 sp.), Mechanitis (4 sp.), Ceratina (32 sp.), Dircenna (10 sp.), and Lycorea (4 sp.). Florida, Louisiana, and Southern California, mark the northern extent of these insects.
Family 2.—SATYRIDÆ. (60 Genera, 835 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 |
This family has an absolutely universal distribution, extending even into the Arctic and Antarctic regions. Many of the genera are, however, restricted in their range.
Hætera, Lymanopoda, Calisto, Corades, Taygetis, Pronophila, Euptychia, and some allied forms (25 genera in all) are Neotropical, the last named extending north to Canada; Debis, Melanitis, Mycalesis and Ypthima, are mostly Oriental, but extending also into the Australian and the Ethiopian regions; Gnaphodes, Leptoneura, and a few other small genera, are exclusively Ethiopian; Xenica, Hypocista, and Heteronympha, are Australian; Erebia, Satyrus, Hipparchia, Cœnonympha, and allies, are mostly Palæarctic, but some species are Ethiopian, and others Nearctic; Chionabas, is characteristic of the whole Arctic regions, but is also found in Chili and the Western Himalayas. The peculiar genera in each region are,—Neotropical, 25; Australian, 7; Oriental, 11; Ethiopian, 5; Palæarctic, 3; Nearctic, 0.
Family 3.—ELYMNIIDÆ. (1 Genus, 28 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — — — — | — — — — | — — — — | — 2 — — | — — 3. 4 | 1 — — — |
The genus Elymnias, which constitutes this family, is characteristic of the Malayan and Moluccan districts, with some species in Northern India and one in Ashanti. It thus agrees with several groups of Vertebrata, in showing the resemblance ​of Malaya with West Africa independently of the Peninsula of India.
Family 4. MORPHIDÆ. (10 Genera, 106 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3 — | — — — — | — — — — | — — — — | — — 3. 4 | 1 — 3 — |
The Morphidæ are a group of generally large-sized butterflies, especially characteristic of the Malayan and Moluccan districts, and of Tropical America; with a few species extending to the Himalayas on the west, and to Polynesia on the east. The genera are:—
Amathusia (6 sp.), Northern India to Java; Zeuxidia (9 sp.), the Malay district; Discophora (7 sp.), Northern India to Philippines, Java and Timor; Enispe (3 sp.), Northern India; Hyades (15 sp.), Moluccan and Polynesian districts, except one species in Java; Clerome (11 sp.), Northern India to Philippines and Celebes; Æmona (1 sp.), Sikhim; Hyantis (1 sp.), Waigiou; Thaumantis (10 sp.), Indo-Chinese and Malayan districts; Morpho (40 sp.), Neotropical region, Brazilian and Central American sub-regions.
Family 5. BRASSOLIDÆ. (7 Genera, 62 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3 — | — — — — | — — — — | — — — — | — — — — | — — — — |
The Brassolidæ have the same distribution as the genus Morpho. The genera are:—
Brassolis (5 sp.); Opsiphanes (17 sp.); Dynastor (2 sp.); Penetes (1 sp.); Caligo (21 sp.); Narope (5 sp.); and Dasyopthalma (3 sp.)
Family 6.—ACRÆIDÆ. (1 Genus, 90 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3 — | — — — — | — — — — | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2 — — |
The genus Acræa is especially abundant in the Ethiopian region, which contains two-thirds of all the known species; 3 or 4 species only, range over the whole Oriental, and most of the Australian regions; while all the rest inhabit the same districts of the Neotropical region as the Brassolidæ.
Family 7.—HELICONIDÆ. (2 Genera, 114 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3. 4 | — — 3 — | — — — — | — — — — | — — — — | — — — — |
The true Heliconidæ are very characteristic of the Neotropical region; one species only extending into the Southern States of North America as far as Florida. The genus Heliconius (83 sp.), has the range of the family; while Eueides (19 sp.), is confined to the Brazilian and Central American sub-regions.
Family 8.—NYMPHALIDÆ. (113 Genera, 1490 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 |
This is the largest and most universally distributed family of butterflies, and is well illustrated by our common Fritillaries, ​Tortoise-shell, Peacock, Painted Lady, and Purple Emperor butterflies. They are found wherever butterfly-life can exist, and some single species—like the Painted Lady (Pyrameis cardui)—range almost over the globe. A few of the more extensive and remarkable genera only, can be here noticed:—
Colænis, Agraulis, Eresia, Synchloe, Epicalia, Eunica, Eubagis, Catagramma, Callithea, Ageronia, Timetes, Heterochroa, Prepona, Hypna, Paphia, and Siderone, are wholly Neotropical, as well as many others which have a smaller number of species. Euryphene, Romaleosoma, Aterica, and Harma, are exclusively Ethiopian. Terinos, Athyma, Adolias, and Tanæcia, are Oriental, but they mostly extend into the Moluccan region; the last however is strictly Malayan, and Adolias only reaches Celebes. Mynes alone, is exclusively Australian, but Prothoe is almost so, having only one outlying species in Java. Eurytela and Ergolis are confined to the Oriental and Ethiopian regions, but the latter reaches the Moluccas. Cethosia, Cirrhochroa, Messaras, and Symphædra, are both Oriental and Australian; while Junonia, Cyrestis, Diadema, Neptis, and Nymphalis, are common to the three tropical regions of the Eastern Hemisphere, the latter extending into the Mediterranean district, while Junonia occurs also in South America and the Southern United States.
The most cosmopolitan genus is Pyrameis, which has representatives in every region and every district. Apatura is found in all but the Ethiopian and the Australian, although it just enters the confines of the latter region in Celebes; Limenitis is abundant in the Oriental region, but extends eastward to Celebes and westward into Europe, North America, and even into South America. Argynnis, Melitæa, and Vanessa, are almost confined to the Palæarctic and Nearctic regions; the former however occurs in the Himalayas and in the mountains of Java, and also in Chili and in Jamaica. Two genera—Dicrorrhagia and Helcyra—have both one species in North India and another in the island of Ceram. The number of genera peculiar to each region is as follows:—Neotropical, 50; Australian, 2; Oriental 15; Ethiopian, 14; Palæarctic, 1; Nearctic, 0.
Family 9.—LIBYTHEIDÆ. (1 Genus, 10 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2 — 4 | — 2.3 — | 1. 2 — — | — 2 — 4 | 1. 2. 3. 4 | 1 — — — |
The genus Libythea, which constitutes this family, appears to have its head-quarters in the Oriental region, but extends on all sides in an erratic manner, into various remote and disconnected portions of the globe, as indicated above.
Family 10.—NEMEOBIIDÆ. (12 Genera, 145 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3 — | — — — — | 1 — — — | — 2 — 4 | — — 3. 4 | 1 — — — |
This group has been separated from the Erycinidæ of the older authors, and contains all the non-American genera and species. Half the genera and nearly four-fifths of the species of this group are, however, Neotropical; one is European; two or three African; and twenty-six Oriental and Australian. The genera are:—
Nemeobius (1 sp.), Europe; Dodona (6 sp.), North India; Zemeros (2 sp.), North India and Malaya; Abisara (11 sp.), North India, Malayan and Moluccan districts, Madagascar and West Africa; Taxila (8 sp.), North India and Malaya; Dicallaneura (2 sp.), Moluccan district; Alesa (6 sp.), Eunogyra (2 sp.), Cremna (7 sp.), Bæotis (3 sp.), are all from the Brazilian sub-region; Eurybia (10 sp.), Mesosemia (80 sp.), inhabit both the Brazilian and Mexican sub-regions.
Family 11.—EURYGONIDÆ. (2 Genera, 78 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3 — | — — — — | — — — — | — — — — | — —- — | — — — — |
This small family, separated from the true Erycinidæ by Mr. Bates, is confined to the tropical forest-districts of continental America. The genera are:—
Eurygona (71 sp.); Methonella (1 sp.); the latter found in Equatorial South America.
Family 12.—ERYCINIDÆ. (59 Genera, 560 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3. 4 | 1. 2. 3 — | — — — — | — — — — | — — — — | — — — — |
This extensive family of small, but exquisitely beautiful butterflies, is especially characteristic of the virgin forests of the Neotropical region, only a few species of three genera extending into the Nearctic region. The more important genera, and those which have an exceptional distribution, can alone be here noticed. Charis extends from Brazil to New York; Apodemia from Brazil to California, Utah, and Oregon; Amarynthis inhabits the Brazilian and Antillean sub-regions; Lepricornis and Metapheles are small genera found only in the Mexican sub-region; Lymnas, Necyria, Ancyluris, Diorhina, Esthemopsis, Anteros, Emesis, Symmachia, Cricosoma, Calydna, Lemonias, Nymphidium, Theope, and Aricoris are common to the Brazilian and Mexican sub-regions. All the other genera (40 in number) are only known from the Brazilian sub-region, and of these a considerable proportion are confined to the damp equatorial forests of the Amazon Valley.
Family 13.—LYCÆNIDÆ. (39 Genera, 1,220 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 |
The Lycænidæ—of the variety and beauty of which in tropical regions our own "Blues" and "Coppers" give but a faint idea—are a group of universal distribution. We shall therefore indicate those genera which are restricted to one or more regions, or are nearly cosmopolitan. The large genus Polyommatus (containing 325 species) has the same universal distribution as the entire family. Our common "Blues" well represent this genus. Lycæna (comprising the "Coppers") is more especially characteristic of the Palæarctic and Nearctic regions, but straggling species occur also in North India, South Africa, Chili, and New Zealand. Thecla is especially characteristic of the Neotropical region, where there are about 370 species; in the Nearctic region, 36; in the Palæarctic 13; and in the Ethiopian 3. Miletus, Lucia, Hypolycæna, Myrina, and Deudorix are common to the three tropical regions of the Eastern Hemisphere—the Ethiopian, Oriental, and Australian. Aphneus and Iolaus are common to the Ethiopian and Oriental regions, the latter extending to Celebes. Ialmenus, Pseudodipsas, Curetis, and Amblypodia are common to the Oriental and Australian regions, but the first-named is found also in Madagascar. Zephyrus is found only in the Nearctic and Palæarctic, Eumæus in the Nearctic and Neotropical regions. The Nearctic region has one peculiar genus (Feniseca); the Palæarctic has two—Thestor and Læosopis; the Ethiopian has nine—Pentila, Liptena, D'Urbania, Axiocerces, Capys, Phytala, Epitola, Hewitsonia, and Deloneura; the Oriental has five—Allotinus, Ilerda, Poritia, Camena, and Liphyra; the Australian has three—Hypochrysops, Utica, and Ogyris; and the Neotropical also three—Lamprospilus, Theorema, and Trichonis.
Family 14.—PIERIDÆ. (35 Genera, 817 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3 — |
The Pieridæ are distributed almost, if not quite, as widely over the globe as the last family, and we shall group the genera in the same manner. Pieris (130 sp.) is cosmopolitan; Terias and Callidryas are found in all the four tropical regions, and as far north as Pennsylvania in the Nearctic region; Pontia, Tachyris, Eronia, and Thestias are common to the Ethiopian, Oriental, and Australian regions, the last-named, however, only extending as far as Timor; Colias is pre-eminently Palæarctic and Nearctic, with a few Ethiopian species, one Indian, two in Chili, and one in the Sandwich Islands; Anthocharis is wholly Palæarctic and Nearctic; Midea has two species Nearctic, and one in Japan; Gonepteryx is Palæarctic and Neotropical, extending into Texas; Idmais and Callosune are Ethiopian and Oriental; Thyca and Iphias are Oriental and Australian; Meganostoma is Nearctic and Neotropical; Nathalis and Kricogonia are Neotropical, ranging into Florida, Texas, and Colorado.
The peculiar genera are pretty equally distributed. The Neotropical region has ten, two being confined to Chili; Euterpe and Leptalis are the most remarkable, the latter containing a number of forms mimicking the Heliconidæ and Danaidæ. The Oriental region has two, Prioneris and Dercas, the Australian one, Elodina; the Ethiopian two, Teracolus and Pseudopontia; the Palæarctic two, Leucophasia and Zegris; the Nearctic one, Neophasia.
Family 15.—PAPILIONIDÆ. (13 Genera, 455 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 |
The Papilionidæ, comprising many of the noblest and richest-coloured butterflies, and long placed at the head of the group, are almost as universally distributed as the Pieridæ, but they do not extend to so many remote islands nor so far into the Arctic and Antarctic regions. Nine-tenths of the species belong to the genus Papilio, and these are especially abundant in tropical regions, although species occur in every region and every sub-region. Well-marked sub-divisions of this large genus are characteristic of each great region—as the "Æneas" group in the Neotropical, the "Paris" group in the Oriental, the "Ægeus" group in the Australian, the "Zenobius" group in the Ethiopian, and many others. The few species of the Palæarctic region belong, on the other hand, to a group of universal distribution, and the Nearctic has a good number of species allied to Neotropical forms.
The other genera have mostly a very restricted range. Parnassius is an Alpine genus, confined to the Palæarctic and Nearctic regions. The Palæarctic region further possesses 5 peculiar genera—Mesapia, Hypermnestra, Doritis, Sericinus, and Thais; the Oriental has 4, Calinaga, Teinopalpus, Bhutanitis, and Leptocircus, the latter going as far as Celebes; the Australian has 1, Eurycus; and the Neotropical 1, Euryades, confined to the Chilian sub-region. The Ethiopian and the Nearctic regions have no peculiar genera.
Family 16.—HESPERIDÆ. (52 Genera (?), 1,200 Species.)
General Distribution. :
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 | 1. 2. 3. 4 |
The Hesperidæ, or Skippers, are an immense group of mostly small obscurely coloured butterflies, universally distributed, and of which hosts of species still remain to be discovered and described. As the grouping of these into genera is not yet satisfactorily accomplished, only the more extensive and best known groups will be here noticed. Pamphila and Hesperia are universally distributed; Nisoniades seems to be only absent from the Australian region. The Neotropical region is pre-eminently rich in Hesperidæ, 33 genera being found there, of which 20 are peculiar to it; the Australian region has 12 genera, only 1 (Euschemon) being peculiar; the Oriental has 18, with 3 peculiar; the Ethiopian, 13, with 3 peculiar; the Palæarctic 6, with 1 (Erynnis) almost peculiar, a species occurring in Mexico; the Nearctic 9, with none peculiar, 4 being found also in the Neotropical region, 2 in the Palæarctic, and the rest being of wide distribution. Many new genera have, however, been recently described in the United States, but it is impossible yet to determine how many, if any, of these are peculiar. More than 100 species of the family are included in Mr. Edwards' "Synopsis of North American Butterflies,"—a very large number considering that Europe possesses only about 30.
Sub-order—Lepidoptera Heterocera, or Moths.
The Lepidoptera Heterocera, or Moths, are of such immense extent, and are, besides, so imperfectly known compared with the Butterflies, that it would serve no purpose to go into the details of their distribution; especially as most of the families and a considerable number of the genera are cosmopolitan. We propose therefore to notice only the Sphingina, which, being generally of large size and finely marked or coloured, and many of them day-fliers, have been extensively collected; and whose numbers are more manageable than the succeeding groups.
Group I.—SPHINGINA.
Family 17.—ZYGÆNIDÆ (46 Genera, about 530 Species).
The Zygænidæ are universally distributed, but many of the genera are restricted in their range. Zygæna (85 sp.) is mainly Palæarctic, but 2 species are South African, and 1 North American; Procris (22 sp.) has a scattered distribution, from the Palæarctic region to South America, South Africa and North India; Heterogynis (3 sp.) and Dysauxis (3 sp.) are European; Pollanisus (3 sp.) is Australian; Glaucopis (120 sp.) is mainly Neotropical, with a few Oriental; Syntomis (94 sp.) is found in all the Old-World regions; and Euchromia (150 sp.) is found in all warm countries, though especially abundant in South America.
Family 18.—CASTNIIDÆ (7 Genera, 63 Species).
The Castniidæ have an interesting distribution, being mainly Neotropical, with four genera in Australia and New Guinea. Castnia, Coronis, and Gazera, with 51 species, are Neotropical; Synemon, Euschemon, Damias and Cocytia, with 12 species, are Australian, the latter being found only in the Papuan Islands.
Family 19.—AGARISTIDÆ (13 Genera, 76 Species).
The Agaristidæ are beautiful diurnal moths, allied to the Castniidæ, but almost confined to the Australian and Oriental regions, with a few in the Ethiopian. The most important genera are,—Agarista (21 sp.), Australia and New Guinea; Eusemia (31 sp.), Ægocera (7 sp.), Oriental and Ethiopian regions; the other genera being confined to the islands from Java to New Guinea.
Family 20.—URANIIDÆ (2 Genera, 12 Species).
These magnificent insects have a singular distribution. The gold-spangled Urania (6 sp.) is characteristic of Tropical America, but a single species of great magnificence occurs in Madagascar. The large but sober-tinted Nyctalemon (6 sp.) is found in the Neotropical, Oriental, and Australian regions.
Family 21.—STYGIIDÆ. (3 Genera, 14 Species.)
These insects are confined to the Palæarctic and Neotropical regions, 2 genera in the former, 1 in the latter.
Family 22.—ÆGERIIDÆ. (24 Genera, 215 Species.)
This family is found in all parts of the world except Australia. Ægeria is most abundant in Europe, but is found also in North and South America.
Family 23.—SPHINGIDÆ. (40 Genera, 345 Species.)
The Sphinx Moths are cosmopolitan. The most important genera are,—Macroglossa (26 sp.), Chærocampa (46 sp.), and Macrosila (21 sp.), all cosmopolitan; Sesia (12 sp.), Europe, Asia, and North America; Deilephila (19 sp.), Palæarctic and Oriental regions, Nearctic region, and Chili; Sphinx (21 sp.), Europe, ​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 (Castniidæ) 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 Lycæna in New Zealand, while Colias ranges to Southern Africa, Malabar, and 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, Solenodon, 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, Tanæcia, Eurytela, Ilerda, Zemeros, Taxila, 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 Lycænidæ. 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 other, have food-plants 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.)
Order—COLEOPTERA.
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 Peridexia, 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, Platychile 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 ​the earth which have been found best to represent the facts of distribution in the higher animals.
CARABIDÆ. (620 Genera, 8500 Species.)
The enormous extent of this family, necessitates a somewhat general treatment. It has been very extensively collected, while its classification has been most carefully worked out, and a detailed exposition of its geographical distribution by a competent entomologist would be of the greatest interest. A careful study of Gemminger and Harold's Catalogue, however, enables me to sketch out the main features of its distribution, and to detail many of its peculiarities with considerable accuracy.
The Carabidæ are remarkable among insects, and perhaps among all terrestrial animals, as being a wonderfully numerous, varied, conspicuous, and beautiful group, which is pre-eminently characteristic of the Palæarctic region. So strikingly and unmistakably is this the case, that it must be held completely to justify the keeping that region distinct from those to which it has at various times been proposed to join it. Although the Carabidæ are thoroughly well represented by hosts of peculiar genera and abundant species in every part of the world without exception, yet the Palæarctic region alone contains fully one-third, or perhaps nearer two-fifths, of the whole. It may also be said, that the group is a temperate as compared with a tropical one; so that probably half the species are to be found in the temperate and cold regions of the globe, leaving about an equal number in the much more extensive tropical and warm regions. But, among the cold regions, the Palæarctic is pre-eminent. North America is also rich, but it contains, by far, fewer genera and fewer species.
The magnificent genus Carabus, with its allies Procerus and Procrustes, containing about 300 species, all of large size, is almost wholly confined to the Palæarctic region, only 10 species inhabiting North America, and 11 Temperate South America, with one on the African mountain of Kilimandjaro. Twelve large genera, containing together more than 2000 species, are truly cosmopolitan, inhabiting both temperate and tropical ​countries all over the globe; but many of these are more abundant in the Palæarctic region than elsewhere. Such are Scarites, Calosoma, Brachinus, Cymindis, Lebia, Chlænius, Platynus, Harpalus, Bembecidium, Pæcilus, and Argutor. Of tropical cosmopolites, or genera found in all the tropical regions, but not in the temperate zones, there seem to be only four,—Catascopus, Coptodera, Colopodes, and Casnonia. Pheropsophus is confined to the tropics of the Old World; while Drimostoma, though widely scattered, is characteristic of the Southern Hemisphere.
The Palæarctic region has about 50 genera of Carabidæ which are strictly confined to it, the most important being,—Leistus (30 sp.), Procerus (5 sp.), Procrustes, (17 sp.), Zabrus (60 sp.), Pristonychus (42 sp.), and Ophonus (60 sp.); but it possesses a large number in common with the Nearctic region. The more remarkable of these are,—Carabus, Nebria, Amara, Cyrtonotus, Bradycellus, Anopthalmus, Celia, Cychrus, Patrobus, Elaphrus, Notiophilus, Bradytus, Callisthenus, Blethisa, and several others. Many too, though not strictly confined to the North Temperate regions, are very abundant there, with a few species isolated in remote countries, or widely scattered, often in an eccentric manner. Among these may be mentioned, Trechus (120 sp.), all North Temperate but 8, which are scattered in Java, New Caledonia and South America; Dyschirus (127 sp.), North Temperate, with 3 or 4 species in Australia, China and La Plata; Omaseus, (88 sp.), Steropus (90 sp.), Platysoma (114 sp.), and Pterostichus (138 sp.), are mostly North Temperate, but each has a few species in the South Temperate zone, New Zealand, Australia, Chili, and the Cape of Good Hope. Dromius (54 sp.), is about two-thirds Palæarctic, the rest of the species being scattered over the world, in Chili, North and South America, South Africa, Burmah, Ceylon, and New Zealand. The North Temperate genera Calathus and Olisthopus, have each one species in New Zealand; Percus has most of its species in South Europe, but 3 in Australia; Abax is confined to the north temperate zone, but with one species in Madagascar; while Læmosthenes is said to have a species identically the same in South Europe and Chili. Some of these apparent anomalies may be due to wrong ​determination of the genera, but there can be little doubt that most of them represent important facts in distribution.
The Nearctic region is comparatively poor in Carabidæ. Its more important peculiar genera are,—Dicælus (22 sp.), Pasimachus (17 sp.), Eurytrichus (9 sp.), Sphæroderus (7 sp.), Pinacodera (6 sp.), and others of smaller extent, about 30 in all. It also possesses representatives of a considerable number of Palæarctic genera, as already indicated; and a few of South American genera, of which Helluomorpha and Galerita are the most important.
The Neotropical region is very rich in peculiar forms of Carabidæ, as in almost all other great groups. It possesses more than 100 peculiar genera, but about 30 of these are confined to the South Temperate sub-region. The more important peculiar genera of Tropical America are,—Agra (144 sp.), Ardistomus (44 sp.), Schizogenius (25 sp.), Pelecium, (24 sp.), Calophena (22 sp.), Ctenodactyla (7 sp.). Among the Chilian and South Temperate peculiar forms are,—Antarctia (29 sp.), Scelodontis (10 sp.), Tropidopterus (4 sp.). Among the Neotropical genera with outlying species are,—Pachyteles (50 sp.), one of which is West African; Selenophorus (70 sp.), with 4 African, 4 Oriental, and 1 from New Caledonia; Ega (11 sp), with one in the East Indies, and one in New Caledonia; Galerita, with 36 American species, 8 African, and 3 Indian; Callida and Tetragonoderus, mostly American, but with a few African, Oriental and Australian species; and Pseudomorpha, common to America and Oceania.
The Australian region is almost equally rich, possessing about 95 peculiar genera of Carabidæ, no less than 20 of which are confined to New Zealand. The most important are, Carenum, Promecoderus, Scaraphites, Notonomus, Ænigma, Sphallomorpha, Silphomorpha, and Adelotopus. The gigantic Catadromus has 4 Australian species and 1 in Java; Homalosoma has 31 species in Australia and New Zealand, and 1 in Madagascar. Celebes and New Guinea have each peculiar genera, and one is common to Australia and the Cape of Good Hope.
The Oriental region possesses 80 peculiar genera, 10 of which are confined to Ceylon. The more important are,—Pericallus, Planetes, and Mormolyce. Distrigus is also characteristic of this ​region, with one species in Madagascar; while it has Orthogonius, Hexagonia, Macrochilus, and Thyreopterus in common with the Ethiopian region, and is rich in the fine tropical genus, Catascopus.
The Ethiopian region has 75 peculiar genera, 8 of which are confined to Madagascar. The more important are,—Polyhirma, Graphipterus, and Piezia. Anthia is chiefly African, with a few species in India; Abacetus is wholly African, except a species in Java, and another in South Europe; and Hypolithus is typically African, but with 7 species in South America and 1 in Java.
The facts of distribution presented by this important family, looked at broadly, do not support any other division of the earth into primary regions than that deduced from a study of the higher animals. The amount of speciality in each of these regions is so great, that no two of them can be properly united; and in this respect the Carabidæ accord wonderfully with the Vertebrates. In the details of distribution there occur many singular anomalies; but these are not to be wondered at, if we take into consideration the immense antiquity of Coleopterous insects—which existed under specialised forms so far back as the Carboniferous epoch,—the ease with which they may be dispersed as compared with larger animals, and the facilities afforded by their small size, habits of concealment, and often nocturnal habits, for adaptation to the most varied conditions, and for surviving great changes of surface and of the surrounding organic forms. The wonder rather is, not that there are so many, but so few cases of exceptional and anomalous distribution; and the fact that these creatures, so widely different from Vertebrates in organisation and mode of life, are yet on the whole subject to the same limitations of range as were found to occur among the higher animals, affords a satisfactory proof that the principles on which our six primary regions are founded, are sound; and that they are well adapted to exhibit the most interesting facts of geographical distribution, among all classes of animals.
Much stress has been laid on the fact of a few species of such typical European genera as Carabus, Dromius, and others, being ​found in Chili and Temperate South America; and it has been thought, that in a system of Entomological regions this part of the world must be united to the Northern Hemisphere. But these writers omit to take into account, either the large numbers of isolated and peculiar forms characteristic of South Temperate America, or the indications of affinity with Tropical America and Australia, both of which are really more important than the connection with Europe. The three important Chilian genera, Cascelius, Barypus, and Cardiopthalmus, are closely allied to the Australian Promecoderus; others, as Omostenus and Plagiotelium, are quite isolated; while Antarctia and Metius, according to Lacordaire, form a distinct division of the family. Chili, too, has many species of Pachyteles, Coptodera, and other South American genera; and this affinity is far stronger in many other families than in the Carabidæ. The existence of representatives of typical northern forms in Chili, is a fact of great interest, and may be accounted for in a variety of ways; (see Vol. II. p. 44) but it is not of such a magnitude as to be of primary importance in geographical distribution, and it can only be estimated at its fair value, by taking into account the affinities of all the groups inhabiting that part of the world.
LUCANIDÆ. (45 Genera, 529 Species.)
Passing over a number of obscure families, we come to the remarkable group of the Lucanidæ, or Stag-beetles, which, being almost all of large size, and many of them of the most striking forms, have been very thoroughly collected and assiduously studied.
The most curious feature of their general distribution, is their scarcity in Tropical South America, and their complete absence from Tropical North America and the West Indian Islands, though they appear again in Temperate North America. In the New World they may, in fact, be looked upon as a temperate group characteristic of the extra-tropical regions and the highlands; while in the Old World, where they are far more abundant, they are distinctly tropical, being especially numerous ​in the Oriental and Australian regions. No genus has the range of the whole family, Dorcus and Lucanus being absent from Africa, while Cladognathus is unknown in the New World and on the continent of Australia. The Oriental region is the richest in peculiar forms, possessing 16 genera, 7 of which are wholly confined to it, while 3 others only just range beyond it to North China on the one side, or to the Austro-Malayan islands on the other. The Australian region comes next, with 15 genera, of which 7 are wholly peculiar. South America has 12 genera, 10 of which are peculiar. The Ethiopian region has 10 genera, 7 of which are peculiar, and 2 of these are confined to the island of Bourbon. The Palæarctic region has 8 genera, and the Nearctic 5; one genus being peculiar to Europe, and two confined to Europe and North America. The Ethiopian and Oriental regions have 3 genera in common and peculiar to them; the Oriental and Australian 3; while the Australian and Neotropical have 1 in common, to which may be added Streptocerus, which represents in Chili the Australian Lamprima.
Among the special features presented by the distribution of the Lucanidæ, may be mentioned—the remarkable group of genera, Pholidotus, Chiasognathus, and Sphenognathus, confined to Temperate South America, the Andes, and mountains of Brazil; Lucanus (19 sp.), almost confined to the Oriental and Palæarctic regions, three species only inhabiting North America; Odontolabris (29 sp.), wholly Oriental, with 2 sp. in Celebes; Nigidius (11 sp.), Ethiopian, but with species in Formosa, the Philippines, and Malacca; Syndesus (11 sp.), common to Australia, New Caledonia, and South America; Figulus (20 sp.), divided between Africa and Madagascar on the one hand, and Australia, with the Malay and Pacific Islands, on the other.
The facts of distribution here sketched out are in perfect accordance with those of many groups of Vertebrates. The regions are sharply contrasted by their peculiar and characteristic genera; the several relations of those regions are truly indicated; while there is a comparatively small proportion of cases of anomalous or eccentric distribution.
CETONIIDÆ. (120 Genera, 970 Species.)
As representative of the enormous group of the Lamellicorns, which, according to continental entomologists, forms a single family numbering nearly 7,000 species, we take the Cetoniidæ or Rose-Chafers. These comprise a number of the most brilliant and beautifully-coloured insects, including the gigantic Goliathi, which are among the largest of known beetles. They have been assiduously collected in every part of the world, and their classification has been elaborated by many of our most eminent entomologists.
The Cetoniidæ are especially abundant in tropical and warm countries, yet far more so in the Old World than in the New; and in the Old World, the Ethiopian region exhibits a marvellous richness in this family, no less than 76 genera being found there, while 64, or more than half the total number, are peculiar to it. Next in richness, though still very far behind, comes the Oriental region, with 29 genera, 17 of which are peculiar. The Neotropical has only 14 genera, but all except two are peculiar to it, and one of these is not found out of the New World. The Australian region has 11 genera, three only being peculiar. The Palæarctic region has 13, with 4 peculiar; the Nearctic 7, with 2 peculiar. The affinities of the regions for each other, as indicated by the genera confined to two adjacent regions, are in this family somewhat peculiar. The Ethiopian and Oriental show the most resemblance, 6 genera being common and peculiar to the two; the Oriental and the Australian are unusually well contrasted, having only one genus exclusively in common, while 8 genera are found in the Indo-Malay Islands which do not cross the boundary to the Austro-Malayan division, and several others only pass to the nearest adjacent islands; on the other hand, the only large Australian genus, Schizorhina, is found in many parts of the Moluccas, but not further west. The Australian and Neotropical regions exhibit no direct affinity, the nearest ally to the South American Gymnetidæ being Clinteria, an African and Asiatic genus; while not a single genus is common ​to Australia and South America. The Nearctic and Palæarctic regions have 3 genera in common, which are found in no other part of the world.
Among the special features of interest connected with the distribution of this family, we must first notice the exceptional richness of Madagascar, which alone possesses 21 peculiar genera. South Africa is also very rich, having 8 peculiar genera. Stethodesma is very peculiar, being divided between South America and Mexico on the one hand, and West and South Africa on the other. Stalagmosoma is a desert genus, ranging from Persia to Dongola. No genus is cosmopolitan, or even makes any approach to being so, except Valgus, which occurs in all the regions except the Neotropical; and even the family seems to be not universally distributed, since no species are recorded either from New Zealand, the Pacific Islands, or the Antilles.
The facts here brought forward, lead us to the conclusion that the Cetoniidæ are an Old-World tropical family, which had been well developed in Africa and Asia before it spread to Australia and America; and that it is only capable of being freely dispersed in the warmer regions of the earth. This view will explain the absence of affinity between the Australian and Neotropical regions, the only closer connection between which, has almost certainly occurred in the colder portions of the Temperate zone.
BUPRESTIDÆ. (109 Genera, 2,686 Species.)
The next family suited to our purpose is that of the Buprestidæ, consisting as it does of many large and some gigantic species, generally adorned with brilliant metallic colours, and attracting attention in all warm countries. Although these insects attain their full development of size and beauty only in the Tropics, they are not much less abundant in the warmer parts of the Temperate zone. In the Catalogue of the Coleoptera of Europe and the Mediterranean Basin, by M. de Marseul (1863), we find 317 species of Buprestidæ enumerated, although ​the district in question only forms a part of the Palæarctic region, which would thus seem to possess its full proportion of the species of this family. Confining ourselves to the generic forms, we find far less difference than usual between the numbers possessed by the tropical and the temperate regions; the richest being the Australian, with 47 genera, 20 of which are peculiar; and the poorest the Nearctic, with 24 genera, of which 7 are peculiar. The Oriental has 41 genera, 14 of which are peculiar; the Neotropical 39, of which the large proportion of 18 are peculiar; the Ethiopian 27, of which 6 are peculiar; and the Palæarctic also 27, but with 9 peculiar.
A most interesting feature in the distribution of this family, is the strong affinity shown to exist between the Australian and Neotropical regions, which have 4 genera common to both and found nowhere else; but besides this, the extensive and highly characteristic Australian genus, Stigmodera, is closely related to a number of peculiar South American genera, such as Conognatha, Hyperantha, Dactylozodes,—the last altogether confined to Chili and Temperate South America. Here we have a striking contrast to the Cetoniidæ, and we can hardly help concluding, that, as the latter is typically a tropical group, so the present family, although now so largely tropical, had an early and perhaps original development in the temperate regions of Australia, spreading thence to Temperate South America as well as to the tropical regions of Asia and Africa. The Australian and Oriental regions have 4 genera exclusively in common, but they also each possess a number of peculiar or characteristic genera, such as the Indo-Malayan Catoxantha (which has only a single species in the Moluccas) and nine others of less importance; and the exclusively Austro-Malayan genus, Sambus, with five smaller groups, and Cyphogastra, with only 2 Indo-Malay species. The Oriental and Ethiopian regions are very distinct, only possessing the single genus, Sternocera, exclusively in common. The Nearctic and Palæarctic are also distinct, only one genus, Dicerca, being confined to America (North and South) and Europe, a fact which again points to a southern origin for this family, and its comparatively recent extension into the ​North Temperate zone. It must be remembered, however, that in view of the immense geological antiquity of the existing families of Beetles, dating back certainly to the Secondary and probably to the Palæozoic epoch, "comparatively recent" may still be of considerable antiquity.
It is somewhat singular that North and South America have no genera exclusively in common. The connection between South America and Africa seems to be shown,—by the genus Psiloptera, the mass of the species being divided between these regions, with a few widely scattered over the globe; and the American genus Actenodes, which has one species in West Africa. Somewhat allied, is the extensive genus Polybothris, strictly confined to Madagascar. The genus Agrilus is perhaps cosmopolitan, although no species of the family is recorded from New Zealand. Among the peculiarities of distribution we may notice,—the genus Sponsor, with 8 species in the island of Mauritius, 1 in Celebes, and 1 in New Guinea; Ptosima, scattered between the United States, Mendoza in South Temperate America, South Europe, the Philippine Islands, and North China; Polycesta, which besides inhabiting South America, North America, and Europe, has a single species in Madagascar; and Belionota, which has 8 species African, 8 Indo-Malayan, 2 Austro-Malayan, and 1 in California. The extensive genus Acmæodera, is most abundant in the warm and dry portions of the Palæarctic, Ethiopian, and Nearctic regions, with some in the Andes and South Temperate America, a few in Brazil and the West Indies, and 1 said to be from the Philippines. About one-third of the genera (containing more than half the species) have a tolerably extensive range, while the genera confined to single regions contain only about one-fourth of the total number of species.
It will, I think, be admitted, after a careful study of the preceding facts, that the regions and sub-regions here adopted, serve to exhibit, with great clearness, the chief phenomena of distribution presented by this interesting family.
LONGICORNIA. (1,488 Genera, 7,576 Species).
The elegant and admired group of the Longicorn Beetles, is treated by continental authors as a single family, consisting of three sub-divisions—the Prionidæ, Cerambycidæ, and Lamiidæ of English entomologists. These are so closely related, and are so similar in form, habits, and general distribution, that it will be best to consider the whole as one group, noticing whatever peculiarities occur in the separate divisions. The endless structural differences among these insects, have led to their being classed in an unusual number of genera, which average little more than 5 species each; a number far below that in any of the other families we have been considering, and probably below that which obtains in any of the more extensive groups of animals or plants. This excessive subdivision of the genera, a large number of which consist of only one or two species, renders it difficult to determine with precision the relations of the several regions, since the affinities of these genera for each other are in many cases undetermined. A group of such enormous extent as this, can only be properly understood after years of laborious study; we must therefore content ourselves with such results as may be obtained from a general survey of the group, and from a comparison of the range of the several genera, by means of a careful tabulation of the mass of details given in the recent Catalogue of Messrs. Gemminger and Harold and the noble work of Lacordaire.
The proportionate extent of the three families of Longicorns is very unequal; the Prionidæ comprising about 7 per cent., the Cerambycidæ 44 per cent., and the Lamiidæ 49 per cent. of the total number of species; and the genera are nearly in the same proportions, being almost exactly 10, 40, and 50 per cent. of the whole, respectively; or, 135 Prionidæ, 609 Cerambycidæ, and 746 Lamiidæ. The several regions, however, present marked differences in their proportions of these families. In the two North Temperate regions, the Cerambycidæ are considerably more numerous than the Lamiidæ, in the proportion of about 12 to ​9; and in this respect the Neotropical region agrees with them, though the superiority in the proportion of Cerambycidæ is somewhat less. In the Old World tropical regions, however, and in Australia, the Lamiidæ greatly preponderate—being nearly double in the Oriental and Ethiopian regions (or as 11 to 6), while in the Australian it is as 6 to 5. The Prionidæ show a similar difference, though in a less degree; being proportionately more numerous in the North Temperate and Neotropical regions. Now, as regards the North Temperate regions, this difference can be, to some extent explained, by a difference in the habits of the insects. The Lamiidæ, which both in the larva and perfect state have exceedingly powerful jaws, exclusively frequent timber trees, and almost always such as are dead; while the Cerambycidæ, are generally more delicate and have weaker mandibles, and many of the species live on shrubs, dead twigs, foliage, and even on flowers. The immense superiority of the Tropics in the number and variety of their timber trees, and the extent of their forests, sufficiently accounts for their superiority to the Temperate regions in the development of Lamiidæ; but the great excess of Cerambycidæ in South America as compared with the rest of the Tropics, is not to be so readily explained.
Bearing in mind the different proportions of the families, as above noted, we may now consider the distribution of the Longicorns as a whole. In number of generic forms, the Neotropical region, as in so many other groups, has a marked superiority. It possesses 516 genera, 489 of which (or about $^{19}$⁄$_{20}$ of the whole) are peculiar to it. The Australian and Oriental regions come next, and are exactly equal, both possessing 360 genera, and having almost exactly the same proportion (in each case a little less than ¾) peculiar. The Ethiopian region has 262 genera, with about $^5$⁄$_6$ peculiar; the Palæarctic 196, with 51 (rather more than ¼) peculiar; and the Nearctic 111, with 59 (a little more than half) peculiar. The more isolated of the sub-regions are also well characterised by peculiar genera. Thus, Chili with Temperate South America possesses 37, a large proportion being Cerambycidæ; the Malagasi group 26, ​with a preponderance of Lamiidæ; and New Zealand 12, of which the Cerambycidæ are only slightly in excess.
The relations between the Longicorn fauna of the several regions, are such as are in accordance with the dependence of the group on a warm climate and abundant vegetation; and indicate the efficiency of deserts and oceans as barriers to their migration. The Neotropical and Australian regions have only 4 genera in common, but these are sufficient to show, that there must probably once have been some means of communication between the two regions, better adapted to these insects than any they now possess. The Nearctic and Neotropical regions have 5, and the Nearctic and Palæarctic 13 genera in common and peculiar to them, the latter fact being the most remarkable, because no means of inter-communication now exists, except in high latitudes where the species of the Longicorns are very few. The Oriental and Australian regions, on the other hand, are closely connected, by having no less than 52 genera of Longicorns in common and peculiar to them. Most of these are specially characteristic of the Malay Archipelago, often extending over all the islands from Sumatra to New Guinea. This large number of wide-spread genera of course gives a character of uniformity to the entire area over which they extend; and, with analogous facts occurring in other families, has led many entomologists to reject that division of the Archipelago between the Australian and Oriental regions, which has been so overwhelmingly demonstrated to be the natural one in the case of the higher animals. The general considerations already advanced in Chapter II. enable us, however, to explain such anomalies as this, by the great facilities that exist for the transfer from island to island of such small animals, so closely connected with woody vegetation in every stage of their existence. That this is the true and sufficient explanation, is rendered clear by certain additional facts, which those who object to the sharp division of the Indo-Malay and Austro-Malay sub-regions have overlooked.
An analysis of all the Malay Longicorns proves, that besides the 52 genera characteristic of the Archipelago as a whole, there are 100 genera which are confined to one or other of its component ​sub-regions. Many of these, it is true, consist of single species confined to a single island, and we will not lay any stress on these; but there are also several important groups, which extend over the Indo-Malay or the Austro-Malay islands only, stopping abruptly at the dividing-line between them. For example, on the Indo-Malay side we have Euryarthrum, Leprodera, Aristobia, Cœlosterna, and Entelopes, and what is perhaps even more satisfactory, the large genera Agelasta and Astathes, abundant in all the Indo-Malay islands, but having only one or two species just passing the boundary into Celebes. On the other side we have Tethionea, Sphingnotus, Arrhenotus, Tmesisternus (the last three genera abounding from New Guinea to Celebes, but totally unknown further west), Hestima, Trigonoptera, Amblymora, Stesilea, Enes, and the large genus Micracautha, with but a single species beyond the boundary,—30 Austro-Malayan genera in all, each found in more than one island, but none of them extending west of Celebes. Here we have clear proof that the boundary line between the two great regions exists for Longicorns, as well as for all other animals; but in this case an unusually large number have been able to get across it. This, however, does not abolish the barrier, but only proves that it is not absolutely effectual in all cases. Those who maintain that the Malay Archipelago forms a single Coleopterous region, must disprove or explain the instances of limited range here adduced.
Out of nearly 1500 known genera of these insects, only one genus, Clytus, appears to be cosmopolitan. Saperda and Callichroma are the only others that perhaps occur in every region; but these are both wanting over wide tracts of the earth's surface, Saperda being absent from Tropical Africa and the Malay Archipelago; and Callichroma from the Australian region, except one species in Polynesia. Many of the genera of Longicorns have a somewhat wide and scattered distribution, indicative of decadence or great antiquity. Mallodon and Parandra are mostly South American, but have species in Australia and Africa; Oeme is found in Brazil and the United States, with one species in West Africa; Ceratophorus has 2 species in West Africa and 1 in New Zealand. Xystrocera is mostly African, but has single species in ​Borneo, Java, Amboyna and South Australia; Phyton has one species in North America and the other in Ceylon; Philagetes has 2 in South Africa, and 1 in Malacca; Toxotus abounds in North America and Europe, with one species away in Madagascar. Leptura is also North Temperate, but has a species at the Cape, one at Singapore and a third in Celebes. Necydalis has species in North and South America, Europe and Australia. Hylotrupes has 1 species in North America and Europe, and 1 in Australia; Leptocera prefers islands, being found only in Ceylon, Madagascar, Bourbon, Batchian, the New Hebrides, New Caledonia and North Australia; Hathliodes is Australian, with 1 species in Ceylon; Schœnionta has 3 Malayan species, and 1 in Natal. Many other cases equally curious could be quoted, but these are sufficient. They cannot be held to indicate any close relation between the distant countries in which species of the same genus are now found, but perhaps serve to remind us that groups of great antiquity, and probably of great extent, have dwindled away, leaving a few surviving relics scattered far and wide, the sole proofs of their former predominance.
General Observations on the Distribution of Coleoptera.
We have now passed in review six of the most important and best known groups of the Coleoptera or Beetles, comprising about 2,400 genera, and more than 21,000 species. Although presenting certain peculiarities and anomalies, we have found that, on the whole, their distribution is in very close accordance with that of the higher animals. We have seen reason to believe that these great and well-marked groups have a high geological antiquity, and by constantly bearing this fact in mind, we can account for many of the eccentricities of their distribution. They have probably survived changes of physical geography which have altogether extinguished many of the more highly organised animals, and we may perhaps gain some insight into the bearing of those changes, by considering the cross relations between the several regions indicated by them. On carefully tabulating the indications given by each of the groups here discussed, I arrive at the following approximate result. The ​best marked affinities between the regions are those between the Nearctic and Palæarctic,—the Oriental and Australian,—the Australian and Neotropical,—which appear to be about equal in each case. Next comes that between the Ethiopian and Oriental on the one side, and the Ethiopian and Neotropical on the other, which also appear about equal. Then follows that between the Nearctic and Neotropical regions; and lastly, and far the least marked, that between the North Temperate and South Temperate regions. That the relation between the Ethiopian and Neotropical region should be so comparatively well marked, is unexpected; but we must consider that in such a comparison as the present, we probably get the result, not of any recent changes or intermigrations, but of all the long series of changes and opportunities of migration that have occurred during many geological epochs,—probably during the whole of the Tertiary period, perhaps extending far back into the Secondary age.
It appears evident that Insects exhibit in a very marked degree in their actual distribution, the influence both of very ancient and very modern conditions of the earth's surface. The effects of the ancient geographical features of the earth, are to be traced, in the large number of cases of discontinuous and widely scattered groups which we meet with in almost every family, and which, to some extent, obscure the broader features of distribution due to the period during which the barriers which divide the several primary regions have continued to exist. And this, which we may consider as the normal distribution, is still further obscured in those cases where the barriers between existing regions are of such a nature as to admit of the free passage of insects or their larva in a variety of ways, and (what is perhaps of more importance) in which the physical features on both sides of the barrier are so nearly identical, as to admit of the ready establishment of such immigrants as may occasionally arrive. These conditions concur, for some families of insects, in the case of the Oriental and Australian portions of the Malay Archipelago; and it is there that the normal distribution has been sometimes greatly obscured, but never, as we have sufficiently shown, by any means obliterated.