Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/490

Rh 472 REPTILES [DISTKIBUTIOX. Coronellulae are numerous; so arc Colubers, of which Pituoplns is the most characteristic. Freshwater Snakes abound, especially of the genus Tropidonotus. Of Tortricidse three genera have been distinguished. No true Vipers occur, but Pit Vipers are represented by three genera, of which two are Rattlesnakes. After what has been stated already, the affinities of this to other regions can be summed up in a few words. The Reptilian fauna of North and South America forms, with the exception of the Chelonians, a homogeneous whole by which the Neogean division proposed by Sclater for Passerine Birds is well characterized. On the other hand, the Chelonian fauna of North America is entirely distinct from that of South America, and most closely allied to that of India. 6. Tlie Europo- Asiatic Region. Whilst the north of the western hemisphere has at least one order of Reptiles, the Chelonians, by which it is distinguished from the south, the temperate region of the eastern hemisphere possesses no important distinguishing type of Reptile. Its Reptilian fauna is merely an offshoot of those of the two adjoining tropical regions ; and, if we were to add the genera most characteristic of the Palaearctic fauna to either Africa or India, the character of neither would be modified or changed. Thus, so far as Reptiles are concerned, a False- arctic region does not deserve to rank with the other primary regions. The Chelonians are represented by nine species only, viz. : Testudo, 4 species Emys, 3 Trionyx, 2 ,, types which are only specifically distinct from those of the two southern tropical regions. The Land Tortoises are confined to the warmer districts of the western portion, penetrating into the centre of the Siberian sub-region, and entirely absent in the northern and eastern parts ; of Emys one species (E. lutaria] is still found in north-eastern Germany as far north as 54 N. lat. 1 ; and probably some other species will be found in similar latitudes in the little explored Amur country, where also a species of Trionyx ( T. maackii) occurs. The second species of this latter genus which is referable to this region inhabits the Euphrates and Tigris. The recent discovery of an Alligator in central China is a highly interesting fact, but not surprising, when we remember the occur- rence in China of not a few North- American types of Batrachians and Freshwater Fishes. The common African Crocodile still lingers in the Mediterranean district, its presence in Syria having been placed beyond doubt, and its occurrence in Sicily having been asserted on very good authority. The Lacertilians include the only family type which this region has not derived from either Africa or India, viz. , the Anguidse. Two genera of this family, Anguis and Pseudopus,' 2 are widely spread in Europe, and closely allied, the former to the South-American Ophiodes, and the latter to the North-American Ophiosaurus. Lacertidse are abundant as in Africa, and Amphisb&nidfe and Chamasleontidee represented at least in the Mediterranean district. Towards the central parts of Asia the terrestrial Agamidae are con- tinued from north-western Africa, partly with but slight modifica- tions, Phrynocephalus being a specifically Central- Asiatic genus. In the Manchurian sub-region these African types are replaced by some Indian forms, such as Gecko and Tachydromus. The northern range of Lizards in this region extends as far as Lapland (Lacerta vivipara and Anguis fragilis). The most characteristic Ophidian genus of the region is Zamenis, a Colubrine form which is very widely spread, and includes more species (eleven) than any other Palsearctic genus. This genus extends over Arabia, and even into the island of Socptra, without being associated there so far as is known at present with Snakes of an either peculiarly African or Indian type. The total number of Palaearctic Snakes amounts to sixty, of which twelve are poisonous Snakes, viz., nine Viperines and three Halys. The majority inhabit the Mediterranean district and western Asia. Four Typhlops and a single Slcnostoma have been found in the Mediterranean district and Persia. Of the small number of Calamariidss and Coronellidse, Rhyncho- 1 Emys lutaria is one of the Tortoises the range of which has become much restricted in post-Glacial times, its remains having been found in peat beds in Norfolk, Belgium, Denmark, and Sweden, where it is now completely extinct. 2 The isolated occurrence of a species of Pseudopus in Khassia has been mentioned above. calamus, Psilosoma, Lytorliynchus, and Dityixiphis (Socotra) are genera not found beyond this region. Colubridss are comparatively numerous, and show less affinity to African than Indian forms. Besides Zamenis, Coluber and Elaphis occur in four species each, and Rhinechis and AcowbiopMs (Afghanistan) are peculiar genera. Three or four species of Tropidonotus represent the groups of Freshwater Snakes. The Psammophidse are well developed ; besides two species of Psammophis, Taphromctopon and Ceelopeltis are peculiar genera, but not extending into eastern Asia. There is one species of Eryx. One species oiNctja reaches the Caspian. The three species of Halys are Central-Asiatic. 3 . Of the nine species of Viperines six belong to Vipera and Cerastes. Daboia and Echis may be considered to have their head- quarters in this region, but they extend into southern India, and Echis has spread east and west along the barren plains or deserts of North Africa and north-western India. 7. Neio Zealand. The southernmost parts of South New America, Africa, and Australia are not inhabited by a Zeal sufficiently differentiated fauna to be separated from the tropical regions of which they are the continuation. None of the small oceanic islands south of 40 or Tierra del Fuego possess any Reptiles. On the other hand New Zealand is by the possession of ffatteria, the sole living remnant of the extinct order Rhynchocephalia (not to mention other scarcely less important parts of its fauna), so much distinguished from the other regions that it can- not be associated with any of them. Although the climate and other physical conditions seem to be well adapted for the existence of the Chelonian and Ophidian types, neither is represented ; and of Lizards only representatives of the ubiquitous Skinks and Geckos have reached its shores ; but some of the latter must have inhabited New Zealand for a long period, as they belong to a distinct genus, Naultinus, which is peculiar to this group of islands. At the conclusion of this section it will be useful first Res to recapitulate the principal features of the Reptilian f K* faunae for each of the primary regions into which the jr land of the globe has been divided by zoologists, and which nearly coincide with the geographical divisions, and secondly to arrange the regions according to the natural relations as expressed by this class of animals. A division into zones comprising the corresponding parts of both hemispheres cannot be maintained for Reptiles, since the greater portion of the faunae of the temperate are merely the offshoots of tropical faunae, no peculiar types of a higher than generic rank being developed in them. 1. The INDIAN REGION is characterized by Trionycidss and Emydidsa, but few Tcstudinidas. Crocodilidee, with Gavials. Lacer- tilians and Ophidians very numerous. Agamidie chiefly arboreal (Draco), and Varanidte. Pythonidse and Lycodontidee. Ground Snakes, Colubers, Tree Snakes, and Freshwater Snakes abundant in genera. Tropidonotus. Poisonous Snakes in the proportion of species as 1 : 10, and comprising Crotalidas and Elapidse, but only two Vipcridss. 2. The AFRICAN REGION (exclusive of Madagascar) is characterized by Land Tortoises, Trionycidss, and Chclydidaz. Species of Crocodi- lus only. Lacertilians and Ophidians rather numerous. Agamidae chiefly terrestrial ; Lacertidze and Varanidw are well represented. Amphisbtenidie, Gerrhosauridae, and Zonuridse are peculiar to the region. Cliam&lcontidx. Pythonidx and Lycodontidae. True Colubers and Tropidonotus almost absent. Psammophidse. Poison- ous Snakes in the proportion of 1 : 5, comprising Viperidse, and numerous venomous Colubrines. 3. The Eunoro-AsTATic REGION is composed of a mixture of Indian and African generic and family types ; and only a few peculiar genera have their centre of distribution in this part, such as Anguis, Pseudopus, Phrynocephalus, Uromastyx, Stenodactylus, Also- phylax, Ceramodactylus, Scincus, Zamenis, Ceelopeltis, Taphromcto- pon, Daboia, 'Echis, Halys. The majority inhabit the sub-tropical and warmer parts abutting upon the neighbouring tropical regions, and are rapidly reduced in number in the more temperate portion. 4. The TROPICAL PACIFIC REGION possesses one of the terrestrial CheLonian types, Chelydidae, and species of Crocodilus only. 8 Viperine and Crotaline Snakes meet in the centre of the Siberian sub region (Peters, Monatsber. lierl. Ak., 1877, p. 730).