Carabidæ are well represented, there being no less than 94 peculiar genera, of which 19 are confined to New Zealand. The Australian genera of most importance are Carenum (68 species), Promecoderus (27 species), Silphomorpha (32 species), Adelotopus (27 species), Scaraphites (25 species), Notonomus (18 species), Gnathoxys (12 species), Eutoma (9 species), Ænigma (15 species), Lacordairea (8 species), Pamborus (8 species), Catadromus (4 species),—the latter found in Australia and Celebes. Common to Australia and New Zealand are Mecodema (14 species), Homalosoma (32 species), Dicrochile (12 species), and Scopodes (5 species). The larger genera, confined to New Zealand only, are Metaglymma (8 species), and Demetrida (3 species). The curious genus Pseudomorpha (10 species), is divided between California, Brazil, and Australia; and the Australian genera, Adelotopus, Silphomorpha, and Sphallomorpha, form with it a distinct tribe of Coleoptera. These being all confined to the warmer regions, and having so scattered a distribution, are no doubt the relics of a widespread group. The Australian genus, Promecoderus, has, however, closely allied genera (Cascelius and its allies), in Chili and Patagonia; while two small genera confined to the Auckland Islands (Heterodactylus and Pristancyclus) are allied to a group found only in Terra-del-Fuego and the Falkland Islands, (Migadops); and in these cases we may well believe that a direct transmission has taken place by some of the various means already indicated.
In Lucanidæ, Australia is only moderately rich, having 7 peculiar genera. The most important are Ceratognathus and Rhyssonotus, confined to Australia; Lissotes to Australia and New Zealand; Lamprima to Australia and Papua. Mitophyllus and Dendroblax inhabit New Zealand only; while Syndesus is found in Australia, New Caledonia, and tropical South America.
The beautiful Cetoniidæ are poorly represented, there being only 3 peculiar genera;—Schizorhina, mainly Australian, but extending to Papua and the Moluccas; Anacamptorhina, confined to New Guinea, and Sternoplus to Celebes. Lomaptera is very characteristic of the Austro-Malay Islands. This almost tropical family shows no approximations between the Australian and Neotropical faunas.
In Buprestidæ, the Australian region is the richest, possessing no less than 47 genera, of which 20 are peculiar to it. Of these, 15 are peculiar to Australia itself, the most important being Stigmodera (212 species), Ethon (13 species), and Nascio (3 species); Cisseis (17 species), and the magnificent Calodema (3 species), are common to Australia and Austro-Malaya; while Sambus (10 species) and Anthaxomorpha (4 species), with some smaller groups, are peculiarly Austro-Malayan. In this family occur several points of contact with the Neotropical region. Stigmodera is said to have a species in Chili, while there are undoubtedly several allied genera in Chili and South Temperate America. The genus Curis has 5 Australian and 3 Chilian species, and Acherusia has 2 species in Brazil, 1 in Australia. These resemblances may probably have arisen from intercommunication during the warm southern period, when floating timber would occasionally transmit a few larvæ of this family from island to island across the antarctic seas. When the cold period returned, they would spread northward, and become more or less modified under the new physical conditions and organic competition, to which they were subjected.
We now come to the very important group of Longicorns, in which the Australian region as a whole, is very rich, possessing 360 genera, of which 263 are peculiar to it. Of these about 50 are confined to the Austro-Malay Islands, 12 to New Zealand, and the remainder to Australia proper with Tasmania. Of the genera confined to, or highly characteristic of Australia, the following are the most important:—Cnemoplites, belonging to the Prionidæ; Phoracantha, to the Cerambycidæ; Zygocera, Hebecerus, Symphyletes, and Rhytidophora, to the Lamiidæ. Confined to the Austro-Malay Islands are Tethionea (Cerambycidæ): Tmesisternus, Arrhenotus, Micracantha, and Sybra (Lamiidæ); but there are also such Malayan genera as Batocera, Gnoma, Praonetha, and Sphenura, which are very abundant in the Austro-Malay sub-region. A species of each of the Australian genera, Zygocera, Syllitus, and Pseudocephalus, is said to occur in Chili, and one of the tropical American genus, Hammatochærus, in tropical Australia; an amount of resemblance which, as in the case of the Buprestidæ, may be imputed to trans-oceanic migration during the Southern warm period. This concludes our illustrations of the distribution of some of the more important groups of Australian insects; and it will be admitted that we have not met with any such an amount of identity with the fauna of Temperate South America, as to require us to modify the conclusions we arrived at from a consideration of the vertebrate groups.
Land-Shells.—The distribution of many of the larger genera of land-shells is very erratic, while others are exceedingly restricted, so that it requires an experienced conchologist to investigate the affinities of the several groups, and thus work out the important facts of distribution. All that can be done here is to note the characteristic and peculiar genera, and any others presenting features of special interest.
In the great family of the snails (Helicidæ), the only genera strictly confined to the region are, Partula, now containing above 100 species, and ranging over the Pacific from the Solomon Isles on the west, to the Sandwich Islands and Tahiti on the east; and Achatinella, now containing nearly 300 species, and wholly confined to the Sandwich Islands. Pfeifferia is confined to the Philippine Islands and Moluccas; Cochlostyla to the Indo-Malay Islands and Australia; Bulimus occurs in most of the insular groups, including New Zealand, but is absent from Australia.
Among the Aciculidæ, the widely-scattered Truncatella is the only genus represented. Among Diplommatinidæ, Diplommatina is the characteristic genus, ranging over the whole region, and found elsewhere as far as India, with one species in Trinidad. The extensive family Cyclostomidæ, is not well represented. Seven genera reach the Austro-Malay Islands, one of which, Registoma, is confined to the Philippines, Moluccas, New Caledonia, and the Marshall Islands. Omphalotropis is the most characteristic genus, ranging over the whole region; Callia is confined to the Philippines, Ceram, and Australia; Realia to New Zealand and the Marquesas. The genus Helicina alone represents the Helicinidæ, and is found in the whole region except New Zealand. The number of species known from Australia is perhaps about 300; while the Polynesian sub-region, according to Mr. Harper Pease, contains over 600; the Austro-Malay Islands will furnish probably 200; and New Zealand about 100; making a total of about 1,200 species for the whole region.
Australian Sub-regions.
Few of the great zoological regions comprise four divisions so strongly contrasted as these, or which present so many interesting problems. We have first the Austro-Malay Islands, an equatorial forest-region teeming with varied and beautiful forms of life; next we have Australia itself, an island-continent with its satellite Tasmania, both tropical and temperate, but for the most part arid, yet abounding in peculiar forms in all the classes of animals; then come the Polynesian Islands, another luxuriant region of tropical vegetation, yet excessively poor in most of the higher groups of animals as well as in some of the lower; and lastly, we have New Zealand, a pair of temperate forest-clad islands far in the southern ocean, with a very limited yet strange and almost wholly peculiar fauna. We have now to consider the general features and internal relations of the faunas of each of these sub-regions, together with any external relations which have not been discussed while treating the region as a whole.