Page:EB1911 - Volume 23.djvu/191

Rh Sternothaerus, both also in Africa, Podocnemis, which elsewhere occurs in South America only, and several Testudinidae; of these Pyxis is peculiar to Madagascar, while Testudo has furnished the gigantic tortoises of Aldabra, the Seychelles, and recently extinct in Mauritius and Madagascar. Of lizards are present a few Gerrhosauridae and Zonuridae, both African types; the remarkable occurrence of two iguanid genera Chalarodon and Hoplurus, both peculiar to the island; skinks, many geckos, and Uroplates, sole type of the Uroplatinae and an abundance of chameleons, of the genera Chameleon, with ''Ch. parsoni'', the giant of the family, and the small species of Brookesia, a genus peculiar to Madagascar. Of snakes we note Typhlopidae and Glauconiidae, and the remarkable occurrence of Boinae, two of the genus Boa (Pelophilus), one of Corallus on the main island and Casarea on Round Island. There are opisthoglyphous mostly arboreal snakes, and the rest are innocuous colubrines, some few with Indian and African affinities, e.g. Zamenis s. Ptyas, more with apparently S. American relationship, or at least with resemblance in taxonomic characters.

An analysis of this peculiarly compound and deficient fauna gives surprising results, namely, the almost total absence of affinity with the Indian region, close connexion with Africa by the possession of Gerrhosauridae, Zonuridae, Chameleons and Pelomedusidae; lastly, the presence of several tree boas, of Podocnemis and of Iguanidae, i.e. families and genera which we are accustomed to consider as typically neo-tropical. Peculiar to Madagascar, autochthonous and very ancient, is only Uroplates. Ancient are also the tortoises, chameleons, geckos, boas, typhlops, gerrhosaurids and zonurids. The absent families may be as ancient as the others, but most of them, notably Varanus, lacertids and agamids are of distinctly northern, palaeotropical origin, and we can conclude with certainty that they had not spread into S. Africa before Madagascar and its satellites became severed from the continent.

.—The present reptilian fauna of this vast area is composed almost entirely of the leavings of those groups which are now flourishing with manifold differentiations under more genial climes, in Africa and India. Fossils, none too numerous, tell us that it was not always thus, since crocodiles, alligators and long-snouted gavials, all the main groups of chelonians, iguanoids, &c., existed in England, the crocodilians persisting even towards the end of the Tertiary period.

There are no crocodiles now in the Eurasian sub-region, excepting small survivors in the Jordan basin, on the borderland of Africa; but the Yang-tse-Kiang is inhabited by an alligator, A. sinensis, while all its congeners are now in America. This finds, to a certain extent, a parallel in Trionyx, of which one species lives in the Euphrates basin, likewise borderland, and another, T. maacki, in rivers of N. China, e.g. in the Amoor. Of other Chelonians we note several species of Testudo, two of them European; Emys europaea, chiefly in Europe, with the other species E. blandingi in the eastern United States; and a few species of Clemmys, a truly periarctic genus.

Of Lacertilia we exclude the cfiameleon. Of geckos Hemidactylus turcicus extends from Portugal to Karachi; Platydactylus facetanus is at home in most S. Mediterranean countries; Teratoscincus is peculiar to the steppes and deserts of Turkestan and Persia; other geckos in the transitional region from Asia Minor to India. Of Lacertae we have Anguidae, Agamidae, Lacertidae, Amphisbaenidae and Scincidae, most of them in Europe represented by but one or two species. Thus Blanus cinereus in Mediterranean countries, Asia Minor and Syria, represents the Amphisbaenidae which are found nowhere else in Europe or Asia, but plentiful in Africa and both Americas. Of the Anguidae, Anguis fragilis is peculiar to Europe, Ophisaurus apus in S.E. Europe, another in Indo-Burman countries, with the rest of the species in N. America. Of Scincidae few in Europe, e.g. Chalcides s. Seps s. Gongylus, others from Asia Minor eastwards, e.g. Scincus, and Ablepharus in Turkestan. Agamidae do not occur in Europe but they exist in considerable numbers from Asia Minor and Turkestan to China, with Phrynocephalus peculiar to central Asia. Lastly, the Lacertidae, of which several species of Lacerta, Psammodromus, Acanthodactylus in Europe, but the majority in Africa and warmer parts of India; in a similar manner the Manchurian forms are related to Chinese.

The total number of palaearctic snakes amounts to about sixty, the majority living in the Mediterranean countries and in W. Asia. One Typhlops in the Balkan peninsula and in W. Asia, in Persia also Glauconia; Eryx jaculus extends into Greece from S.W. Asia as sole representative of the Boidae. Several vipers, the common viper, V. berus, from Wales to Saghalien Island, V. aspis, V. latastei and V. ammodytes in S. Europe; a pit viper, Ancistrodon, e.g. halys, in the Caspian district, thence this genus through China and again in N. America. Echis extends N. into Turkestan. The Indian cobra ranges N. to Transcaspia and far into China. All the other snakes belong to the aglyphous and opisthoglyphous Colubridae; of the latter Coelopeltis is peculiar to S. Europe and S.W. Asia; Macroprotodon cucullatus to S. Spain, the Balearic Islands and N. Africa; Tephrometopon peculiar to Turkestan and neighbouring countries; none extending into E. Asia. Of the aglyphous colubrines the most characteristic genus is Zamenis incl. Zaocys, very widely spread and including more species than any other palaearctic genus; several species of the wide-ranging genus Tropidonotus, besides Coluber,

with Rhinechis scalaris in S.W. Europe. There are, besides, other genera, especially in the debatable countries of S.W. Asia, Persia and Afghanistan, and speaking generally the colubrines show less affinity to African than to Indian forms, just as we should expect from the prevail in geographical conditions. If it were not for the N.W. corner of Africa and portion of its N. coast, the European fauna would have very little in common with Africa.

.—Of this huge continent only the United States and Mexico come into consideration, since N. of 45° latitude reptilian life is very scarce. The area, however, with these restrictions, is larger than the Indian and Malay countries, and larger than the Australian region. Yet the fauna is comparatively poor, very poor indeed, if it were not for Mexico and the Sonoran province, which seems to be the ancient centre of distribution of much of the present typically N. American fauna.

Characteristic of the area is the abundance of Chelonians and Iguanidae, to which Tejidae have to be added in the S.; equally characteristic is the complete absence of Pleurodirous Chelonians, of Chameleons, Agamidae, Lacertidae, Varanidae and Viperinae. The fauna is composed as follows: Crocodilia, with Crocodilus americanus and Alligator mississippiensis in the S. Of Chelonians the Chelydridae, peculiar to the E. half but for the reappearance of a species of Chelydra in Central America; many Cinosternidae likewise almost peculiar to the area; of Testudinidae an abundance of freshwater forms, notably Chrysemys, and Emys in common with Europe, whilst terrestrial tortoises are extremely scanty, namely one species of Testudo, T. polyphemus, the gopher, and two of Cistudo, e.g. C. carolina; lastly, two Trionyx in the whole of the Mississippi basin and thence N. into Lake Winnipeg, 51° N. Lacertilia: Geckos are very scarce; N. America has received only Sphaerodactylus notatus from the Antilles into Florida, and Phyllodactylus tuberculosus into California from the Pacific side of Mexico; Eublepharinae are absent. Of Iguanidae we have a typically Sonoran set, e.g. Crotaphytus, Holbrookia, Uta, Phrynosoma, Sceloporus, and a S. set of which only Anolis extends out of the tropics. It is significant that only a few species of Sceloporus and Phrynosoma extend into the United States, although far N.; of the large genus Anolis only A. carolinensis enters Texas to Carolina. Sceloporus may be called the most characteristic genus of Sonoraland and Mexico. Of the tropical family of Tejidae only Cnemidophorus, with many species in Mexico, a few in the adjoining N. states, and with C. sexlineatus over the greater part of the Union. Angusdae: Ophisaurus ventralis in the United States; the other species in the Old World. Diploglossus peculiar to mountains of Mexico. Gerrhonotus, the main genus, centred in Mexico, but G. coeraleus ranges from Costa Rica along the Pacific side right into British Columbia, the most northern instance of a New World reptile.

Xenosaurus grandis of Mexican mountains is the monotype of a family, and the same would apply to Heloderma (H. suspectum, the Gila monster of the hottest lowland parts of Arizona and New Mexico; and H. horridum of Mexico) if it were not for Lanthanotus of Borneo. Scincidae: of this cosmopolitan family America possesses the smallest number, and it is significant that the number of species decreases from N. to S.; Eumeces from Minnesota and Massachusetts through Mexico, with many species, and Lygosoma s. Mocoa laterale from S.E. and Central States to Mexico. Xantusiidae, a small family, is composed of a N. or Sonoran and a S. or Central American-Antillean group; e.g. Xantusia of the deserts of Nevada and California. Aniella, monotype of a family of California to El Paso, Texas, i.e. peculiar to Sonoraland, Amphisbaenidae with Rhineura in Florida and the marvellous Chirotes in Lower California and the Pacific side of Mexico; the other members of this family are tropical so far as America is concerned.

Snakes: of Typhlopidae only Anomalepis mexicana, peculiar to Nuevo Leon; of Glauconiidae several extending N. into Texas and Florida. Boinae continue N. as the arenicolous Lichanura of Lower California and Arizona, and the likewise arenicolous Charina bottae which extends from California to the state of Washington; the other members of the family are all tropical, extra-regional. Of Viperidae only pit vipers occur, but of them rattlesnakes cover the whole of the habitable area; Ancistrodon, without a rattle, e.g. the moccasin snake and the water viper, has other species in central and E. Asia. Of Elapinae, far into the E. United States only the genus Elaps with a few species, of which E. fulvius, the commonest, ranges from S. Brazil far into the S. and E. states. A few opisthoglyphous, terrestrial, snakes just enter the United States from Mexico, e.g. Trimorphodon. Of aglyphous colubrines species of genera like or resembling Tropidonotus, Coronella and Coluber, including Pityophis and Spilotes, are abundant, the latter being very characteristic; Ischnognathus and Contia, Ficimia and Zamenis likewise are clearly nearctic, or Sonoran.

The Greater Antilles have essentially neotropical, i.e. Central American and S. American affinities, but there is also some Sonoran infusion.—There is Crocodilus americanus; no Chelonians are natives except one or two Chrysemys. Of Lacertilia, geckos are abundant; of Iguanidae several arboreal forms, notably the large Iguana, and Metopoceras of Haiti, and Cyclura, both peculiar; of Anguidae Celestus, peculiar, but closely allied to Diploglossus; of Xantusiidae the peculiar genus Cricosaura s. Cricolepis. Of