MADAGASCAR  and certain other islands have a

fauna which is as remarkable for its deficiencies as it is for its present forms . The following well-defined groups are absent: Trionychidae and Chelydidae; Agamidae, Lacertidae, Anguidae, Amphisbaenidae, Varanidae and Eublepharinae; all the Viperidae and Elapinae, so that this large island enjoys perfect absence of poisonous snakes, not counting the practically harmless opisthoglyphous tree snakes; there are further no pythons and no ilysias . The actual fauna consists of: Crocodilus vulgaris, which is said to be extremely abundant; of Chelonians, Pelomedusa galeata and ' The same authority enumerates 536 species of reptiles for British India, i.e. about one-sixth of all the recent species of reptiles (Fauna of British India, edit . W . T . Blanford, London, 1890) . 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. parson, 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 relation-ship, 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 .