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altogether peculiar families, and several others which only range into the Nearctic region, as well as a very large number of peculiar or characteristic genera. As the orders of reptiles differ considerably in their distributional features, they must be considered separately. The snakes (Ophidia) differ from all other reptiles, and from most other orders of vertebrates, in the wide average distribution of the families; so that such an isolated region as the Neotropical possesses no peculiar family, nor even one confined to the American continent. The families of most restricted range are— the Scytalidae, only found elsewhere in the Philippine islands; the Amblycephalidae, common to the Oriental and Neotropical regions; and the Tortricidae, most abundant in the Oriental region, but found also in the Austro-Malay islands and Tropical South America. Sixteen of the families of Snakes occur in the region, the Colubridae, Amblycephalidae, and Pythonidae, being those which are best represented by peculiar forms. There are 25 peculiar or characteristic genera, the most important being Dromicus (Colubridae); Boa, Epicrotes, and Ungalia (Pythonidae); Elaps (Elapidae); and Craspedocephalus (Crotalidae). The lizards (Lacertilia) are generally more restricted in their range; hence we find that out of 15 families which inhabit the region, 5 are altogether peculiar, and 4 more extend only to N. America. The peculiar families are Helodermidae, Anadiadae, Chirocolidae, Iphisiadae, and Cercosauridae ; but it must be noted that these all possess but a single genus each, and only two of them (Chirocolidae and Cercosauridae) have more than a single species. The families which range over both South and North America are Chirotidae, Chalcidae, Teidae, and Iguanidae; the first and second are of small extent, but the other two are very large groups, the Teidae possessing 12 genera and near 80 species; the Iguanidae 40 genera and near 150 species; the greater part of which are Neotropical. There are more than 50 peculiar or highly characteristic genera of lizards, about 40 of which belong to the Teidae and Iguanidae, which thus especially characterize the region. The most important and characteristic genera are the following: Ameiva (Teidae); Gymnopthalmus (Gymnopthalmidae); Celestus and Diploglossus (Scincidae); Sphaerodactylus (Geckotidae); Diocephalus, Liolaemus, Proctotretus, and many smaller genera (Iguanidae). The three extensive Old World families Varanidae, Lacertidae, and Agamidae, are absent from the entire American continent. In the order Crocodilia, America has the peculiar family of the alligators (Alligatoridae), as well as several species of true crocodiles (Crocodilidae). The Chelonia (tortoises) are represented by the families Testudinidae and Chelydidae, both of wide range; but there are six peculiar genera-Dermatemys and Stantrotypus belonging to the former family,–Peltocephalus, Podoenemis, Hydromedusa, and Chelys, to the latter. Some of the Amazon river-turtles of the genus Podocnemys rival in size the largest species of true marine turtles (Cheloniidae), and are equally good for food. Amphibia.-The Neotropical region possesses representatives of sixteen families of Amphibia of which four are peculiar; all belonging to Anoura or tail-less Batrachians. The Caeciliadae or snake-like amphibia, are represented by two peculiar genera, Siphonopsis and Rhinatrema. Tailed Batrachians are almost unknown, only a few species of Spelerpes (Salamandridae) entering Central America, and one extending as far south as the Andes of Bogota in South America. Tail-less Batrachians on the other hand, are abundant ; there being 14 families represented, of which 4,-Rhinophryndae, Hylaplesidae, Plectromantidae, and Pipidae are peculiar. None of these families contain more than a single genus, and only the second more than a single species; so that it is not these which give a character to the South American Amphibia-fauna. The most important and best represented families are, Ranidae (true frogs), with eleven genera and more than 50 species; Polypedatidae (tree-frogs) with seven genera and about 40 species; Hylidae (tree-frogs) with eight genera and nearly 30 species; Engystomidae (toads) (5 genera), Bombinatoridae (frogs), (4 genera), Phryniscidae and Bufonidae (toads), (each with 2 genera), are also fairly represented. All these families are widely distributed, but the Neotropical genera are, in almost every case, peculiar.
Fresh-water fishes.—The great rivers of Tropical America abound in fish of many strange forms and peculiar types. Three families, and three sub-family groups are peculiar, while the number of peculiar genera is about 120. The peculiar families are Polycentridae, with two genera; Gymnotidae, a family which includes the electric eels, (5 genera); and Trygonidae, the rays, which are everywhere marine except in the great rivers of South America, where many species are found, belonging to two genera. Of the extensive family Siluridae, three sub-families Siluridae anomalopterae, S. olisthopterae, and S. branchiolae, are confined to this region. The larger and more important of the peculiar genera are the following: Percilia, inhabiting Chilian and Pereichthys South Temperate rivers, belong to the Perch family (Percidae); Acharnes, found only in Guiana, belongs to the Nandidae, a family of wide range in the tropics; the Chromidae, a family of exclusively fresh-water fishes found in the tropics of the Ethiopian, Oriental and Neotropical regions, are here represented by 15 genera, the more important being Acara (17 sp.), Heros (26 sp.), Crenicichla (9 sp.), Satanoperca (7 sp.). Many of these fishes are beautifully marked and coloured. The Siluridae proteropterae are represented by 14 genera, of which Pimelodus (42 sp.), and Platystoma (11 sp.), are the most important; the Siluridae stenobranchiae by 11 genera, the chief being Doras (13 sp.), Auchenipterus (9 sp.), and Oxydoras (7 sp.). The Siluridae proteropodes are represented by 16 genera, many of them being among the most singular of fresh-water fishes, clothed in coats of mail, and armed with hooks and serrated spines. The following are the most important—Chatostomus (25 sp.), Loricaria (17 sp.), Plecostonus (15 sp.) and Callichthys (11 sp.). The Characinidae are divided between Tropical America and Tropical Africa, the former possessing about 40 genera and 200 species. The Haplochitomidae are confined to South America and Australia; the American genus being Haplochiton. The Cyprinodontidae are represented by 18 genera, the most important being, Paecilia (16 sp.), Girardinus (10 sp.), and Gambusia (8 sp.) The Osteoglossidae, found in Australian and African rivers, are represented in South America by the peculiar Arapaima, the “pirarucu" of the Amazon. The ancient Sirenoidei, also found in Australia and Africa, have the Lepidosiren as their American representative. Lastly, Ellipisurus is a genus of rays peculiar to the fresh waters of South America. We may expect these numbers to be largely increased and many new genera to be added, when the extensive collections made by Agassiz in Brazil are described. Summary of Neotropical Vertebrates.—Summarizing the preceding facts, we find that the Neotropical region possesses no less than 45 families and more than 900 genera of Vertebrata which are altogether peculiar to it; while it has representatives of 168 families out of a total of 330, showing that 162 families are altogether absent. It has also representatives of 131 genera of Mammalia of which 103 are peculiar to it, a proportion of #; while of 683 genera of land-birds no less than 576 are peculiar, being almost exactly # of the whole. These numbers and proportions are far higher than in the case of any other region.
The Neotropical region is so excessively rich in insect life, it so abounds in peculiar groups, in forms of exquisite beauty, and in an endless profusion of species, that no adequate idea of this branch of its fauna can be conveyed by the mere enumeration of peculiar and characteristic groups, to which we are here compelled to limit ourselves. Our facts and figures will, however, furnish data for comparison; and will thus enable those who have some knowledge of the entomology of any other country, to form a better notion of the vast wealth of insect life in this region, than a more general and picturesque description could afford them.
Lepidoptera.-The Butterflies of South America surpass those of all other regions in numbers, variety and beauty; and we find here, not only more peculiar genera and families than elsewhere, but, what is very remarkable, a fuller representation of the whole series of families. Out of the 16 families of butterflies in all parts of the world, 13 are found here, and 3 of these are wholly peculiar—Brassolidae, Heliconidae, and Eurygonidae, with a fourth, Erycinidae, which only extends into the Nearctic region; so that there are 4 families peculiar to America. These four families comprise 68 genera and more than 800 species; alone constituting a very important feature in the entomology of the region. But in almost all the other families there are numbers of peculiar genera, amounting in all to about 200, or not far short of half the total number of genera in the world— (431). We must briefly notice some of the peculiarities of the several families, as represented in this region. The Danaidae consist of 15 genera, all peculiar, and differing widely from the generally sombre-tinted forms of the rest of the world. The delicate transparent-winged Ithomias of which 160 species are described, are the most remarkable. Melinaea, Napeogenes, Ceratina and Dircenna are more gaily coloured, and are among the chief ornaments of the forests. The Satyridae are represented by 25 peculiar genera, many of great beauty; the most remarkable and elegant being the genus Haetera and its allies, whose transparent wings are delicately marked with patches of orange, pink, or violet. The genus Morpho is perhaps the grandest development of the butterfly type, being of immense size and adorned with the most brilliant azure tints, which in some species attain a splendour of metallic lustre unsurpassed in nature. The Brassolidae are even larger, but are crepuscular insects, with rich though sober colouring. The true Heliconii are magnificent insects, most elegantly marked with brilliant and strongly contrasted tints. The Nymphalidae are represented by such a variety of gorgeous insects that it is difficult to select examples. Prominent are the genera Catagramma and Callithea, whose exquisite colours and symmetrical markings are unique and indescribable; and these are in some cases rivalled by Agrias and Prepona, which reproduce their style of coloration although not closely allied to them. The Erycinidae, consisting of 59 genera and 560 species, comprise the most varied and beautiful of small butterflies; and it would be useless to attempt to indicate the unimaginable combinations of form and colour they present. It must be sufficient to say that nothing elsewhere on the globe at all resembles them. In Lycaenidae the worldwide genus Thecla is wonderfully developed, and the South