« EelmineJätka »
In the above list the species marked * extend to Tierra del Fuego. It is a remarkable fact that so many of the species belong to genera which are wholly Neotropical, and that the specially South American families of Icteridæ, Tyrannidæ, Dendrocolaptidæ, Pteroptochidæ, Trochilidæ, and Conuridæ, should supply more than one-third of the species; while the purely South American genus Phrygilus, should be represented by four species, three of which abound in Tierra del Fuego.
Plate XVI. A Scene in the Andes of Chili, with characteristic Animals.—The fauna of South Temperate America being most fully developed in Chili, we place the scene of our illustration in that country. In the foreground we have a pair of the beautiful little chinchillas (Chinchilla lanigera), belonging to a family of animals peculiar to the sub-region. There are only two species of this group, both confined to the higher Andes, at about 8000 feet elevation Coming round a projecting ridge of the mountain, are a herd of vicunas (Auchenia vicugna), one of that peculiar form of the camel tribe found in South America and confined to its temperate and alpine regions. The upper bird is a plant-cutter (Phytotoma rara), of sober plumage but allied to the beautiful chatterers, though forming a separate family. Below, standing on a rock, is a plover-like bird, the Thinocorus orbignianus, which is considered to belong to a separate family, though allied to the plovers and sheath-bills. Its habits are, however, more those of the quails or partridges, living inland in dry and desert places, and feeding on plants, roots, and insects. Above is a condor, the most characteristic bird of the high Andes.
Reptiles and Amphibia.—These groups show, for the most part, similar modifications of American and Neotropical forms, as those we have seen to prevail among the birds. Snakes do not seem to go very far south, but several South American genera of Colubride and Dendrophidae occur in Chili; while Enophrys is peculiar to La Plata, and Callorhinus to Patagonia, both belonging to the Colubrida. The Elapide do not extend into the temperate zone; but Craspedocephalus, one of the Crotalidæ, occurs at Bahia Blanca in Patagonia (Lat. 40° S.)
Lizards are much more numerous, and there are several liar and interesting forms. Three families are represented ; Teide by two genera-Callopistes peculiar to Chili, and Ameiva which ranges over almost the whole American continent and is found in Patagonia; Geckotidæ by four genera, two of which,Caudiverbera and Homonota—are peculiar to Chili, while Sphærodactylus and Cubina are Neotropical, the former ranging to Patagonia, the latter to Chili; and lastly the American family Iguanidæ represented by eight genera, no less than six being peculiar, (or almost so,) to the South temperate region. These are Leiodera, Diplolamus and Proctrotretus, ranging from Chili to Patagonia; Leiolæmus, from Peru to Patagonia ; Phrymaturus, confined to Chili, and Ptygoderus peculiar, to Patagonia and Tierra del Fuego. The other two genera, Oplurus and Leiosaurus, are common to Chili and tropical South America.
Tortoises appear to be scarce, a species of Hydromedusa only being recorded. Of the Amphibia, batrachia (frogs and toads) alone are represented, and appear to be tolerably abundant, seventeen species having been collected by Mr. Darwin in this sub-region. Species of the South American genera Phryniscus, Hylaplesia, Telmatobius, Cacotus, Hylodes, Cyclorhamphus, Pleurodema, Cystignathus, and Leiuperus, are found in various localities, some extending even to the Straits of Magellan,—the extreme southern limit of both Reptilia and Amphibia, except one lizard (Ptygoderus) found by Professor Cunningham in Tierra del Fuego. There are also four peculiar genera, Rhinoderma belonging to the Engystomidæ; Alsodes and Nannophryne to the Bombinatoridæ; Opisthodelphys to the Hylidæ; and Calyptocephalus to the Discoglossidæ.
It thus appears, that in the Reptiles all the groups are typically American, and that most of the peculiar genera belong to families which are exclusively American. The Amphibia, on the other hand, present some interesting external relations, but these are as much with Australia as with the North temperate regions. The Bombinatoridæ are indeed Palearctic, but a larger proportion are Neotropical, and one genus inhabits New Zealand. The Chilian genus Calyptocephalus is allied to Australian tropical genera.
The Neotropical genera of Ranidae, five of which extend to Chili and Patagonia, belong to a division which is Australian and Neotropical, and which has species in the Oriental and, Ethiopian regions.
Fresh-water Fishes.--These present some peculiar forms, and some very interesting phenomena of distribution. The genus Percilia has been found only in the Rio de Maypu in Chili; and Percichthys, also belonging to the perch family, has five species confined to the fresh waters of South Temperate America, and one far away in Java. Nematogenys (1 sp.) is peculiar to Chili; Trichomycterus reaches 15,000 feet elevation in the Andes,—both belonging to the Siluridæ; Chirodon (2 sp.), belonging to the Characinidæ, is peculiar to Chili; and several other genera of the sąme family extend into this sub-region from Brazil. The family Haplochitonidæ has a remarkable distribution; one of its genera, Haplochiton (2 sp.), inhabiting Tierra del Fuego and the Falkland Islands, while the other, Prototroctes, is found only in South Australia and New Zealand. Still more remarkable is Galacias (forming the family Galaxidæ), the species of which are divided between Temperate South America, and Australia, Tasmania, and New Zealand; and there is even one species (Galacias attenuatus) which is found in the Chatham Islands, New Zealand, and Tasmania, as well as in the Falkland Islands and Patagonia. Fitzroya (1 sp.) is found only at Montevideo ; Orestias (6 sp.) is peculiar to Lake Titicaca in the high Andes of Bolivia; Jenynsia (1 sp.) in the Rio de la Plata -all belonging to the characteristic South American family of the Cyprinodontidæ.
Insects. It is in insects more than in any other class of animals, that we find clear indications of a not very remote migration of northern forms, along the great mountain range to South Temperate America, where they have established themselves as a prominent feature in the entomology of the country. The several orders and families, however, differ greatly in this respect; and there are some groups which are only represented by modifications of tropical forms, as we have seen to be almost entirely the case in birds and reptiles.