Page:Encyclopædia Britannica, Ninth Edition, v. 22.djvu/209

 SNAKES 193 generally narrow and much imbricate ; ventral scutes keeled later- ally ; double row of sub-caudals. No large fang either in front or in the middle of the upper jaw. African genera : Bucephalus, Hapsidophrys, Rhamnophis, Philo- thamnus, Ithycyi^hus. Indian and Australian genera : Gonyo- soma, Phyllophis, Dcndraphis, Chrysopclea. Tropical American : Ahtetulla. Family 11. DRYOPHID^E (Whip Snakes). Body and tail ex- cessively slender and elongate ; head very narrow and long with tapering snout, which sometimes is produced into a longer or shorter appendage. Mouth very wide. Eye of moderate size, generally with a horizontal pupil. Scales very narrow, much imbricate ; double row of sub-caudals. Posterior maxillary teeth grooved. Genera: Tropidococcyx, Cladophis, Dryophis, Tragops, Passerita (see fig. 10), Langaha. Family 12. DIP.SADID.E. Body much compressed, elongate or of moderate length ; head short, broad behind, with short rounded snout distinct from neck. Eye large, generally with vertical pupil. Cleft of the mouth wide. Scales of the vertebral series frequently enlarged. Dentition strong, frequently with enlarged anterior and posterior maxillary teeth. Genera : Chamsstortus, Leptodira, Tropidodipsas, ffcmidipsas, Thamnodynastes, Dipsas, Dipsadoboa, Rhinobothryum, Pythono- dijjsas. Family 13. SCYTALID^E. Head, trunk, and tail of moderate dimensions. Eye of moderate size, with elliptical pupil. Scales smooth, in seventeen or nineteen rows ; anal entire ; single or double row of sub-caudals. Posterior maxillary teeth grooved, anterior ones equal in length. Genera : Scytale, Oxyrhoput, Hologcrrhum, PseudoxyrJiopus, Rhin'osim'us. Family 14. LYCODOXTIDJE. Body of moderate length or rather elongate ; snout generally depressed, flat, and elongate. Eye rather small, often with vertical pupil. Upper head-shields regular, with the posterior frontals enlarged. Maxillary with a fang in front, but without posterior grooved tooth. African genera : Boodon, Holuropholis, Alopecion, Lycophidium, Botlirophthalmus, Bothrolycus, Lycodryas, Hormonotus, Simo- ccphalus, Lamprophis. Indian genera : Lycodon, Dinodon, Tetragonosoina, Leptorhytaon, Ophites, Ccrcaspis, Ulupc. Family 15. AMBLYCEPHALID.E (Blunt Heads). Body com- pressed, slender, and of moderate length ; head short, thick, vi-ry distinct from neck ; nostril in a single shield. Eye with vertical pupil. Cleft of the mouth narrow ami not veiy extensible. Scales smooth or faintly keeled, those of the vertebral series generally enlarged. Maxillary dentition feeble, no grooved tooth. Indian genera : Dipsadomorus, Amblycep/Mlus, Parcas, Asthcno- dipsas, Elachistodon. South-American genera : LeptoyiHtthus, Opisthophis. Family 16. EitYCiD.E(Sand Snakes). Body of moderate length, cylindrical, covered with small short scales ; tail very short, with a single series of sub-caudals. Eye small, with vertical pupil. None of the labials are pitted. Anterior teeth longest. Adult individuals of some of the species with rudiments of hind limbs. Genera : Eryx, Cursorin, Gongylophis, Bolyeria, Erebophis, Licli- anura, Calabaria, Wenona, Charina. Family 17. BOID..E. Body and tail of moderate length or elon- gate ; tail prehensile ; snout rounded in front. Eye with vertical pupil. Scales in numerous series ; single or double row of sub- caudals. In some of the genera the upper and lower labials are pitted. Teeth strong, unequal in size, none grooved ; no inter- maxillary teeth. Rudiments of hind limbs are generally present. Genera : Boa (see fig. 11), Pclophilus, Xiphosoma, Corallus, Epi- crates, Chilabothrius, Enygnis, Lcptoboa, Ungalia, Trachyboa. Family 18. PYTHOXIP.E (Rock Snakes). Distinguished from the preceding family by the presence of intermaxillary teeth. Genera : Python (see fig. 12), Morclia, Chondropython, Liasis, Aspidiotes, Nardoa, Loxocemus. Family 19. ACROCHORDIDJE (Wart Snakes). Body of moderate length, covered with small, non- imbricate, tubercular or spiny scales ; tail rather short, prehensile. Head covered with scales like the body ; nostrils close together, at the top of the snout. Eye small. Teeth short, strong, sub-equal in size. Aquatic. Vivi- parous. India. Genera : Acrochordus, Chersydrus. Family 20. XENODEUMID^E. Distinguished from the preceding family by possessing broad ventral and sub-caudal scutes. One genus : Xenodcrmus (Java). ? Nothopsis (Central America). Third Sub-order. Ophidii Colubriformes Venenosi. Venomous Colubrine snakes. An erect grooved or perforated tooth in front of the maxillary which is not capable of rotation in its transverse axis. Scales differentiated. A mental groove. Family 1. ELAPID.E. Tail conical, tapering. Head with shield : loreal absent. Venom-fang grooved : maxillary long, with short teeth behind the fang. Genus with wide distribution : Naja (see fig. 13). Indian genera: Callophis, Meg&rophis, JJcmibungartis, Xcnurclaps, Biinyrtrus, Ophiophagiis. African genera : Pcecilophis, Elapsoidea, Cyrt- ophis. South-American genus: Elaps (see fig. 14). Australian genera : Vermicella, Brachysoma, Ncclaps, Brachyurophis, Rhinelaps, Dicmenia, Cacophis, Hoploccphalus, Tropidechis, Pseudechis, Pseudonaja, Pseudohaje, Ogmodon. Family 2. ATRACTASPIDIDJE. Body cylindrical, of moderate pro- portions ; tail short. Head short, not distinct from neck. Mouth narrow. Maxillary short, with perforated poison -fang, without other teeth behind. Africa. Genus : Atractaspis. Family 3. CAUSID*. Body of moderate proportions, tail moderate or rather short. Head distinct from neck. Mouth wide. Maxil- lary short, with perforated poison-fang, without other teeth behind. African genera : Sepcdon, Causus. South- American : Dinodipv^. Family 4. DIXOPHID^E (Venomous Tree Snakes). Body and tail much elongate ; head distinct from neck. Mouth wide. A perforated poison-fang, without other teeth behind. Africa. Genus : Din<>2)his (Dendraspis). Family 5. HYDROPHIIXE (Sea Snakes). Body generally com- pressed, and without broad ventral scutes ; tail compressed, rudder- shaped. Nostrils directed upwards. Poison-fangs small, grooved. Viviparous. Genera : Platurus, Aipysums, Disteira, Acalyptus, Hydrophis, Enhydrina, Pelagophis, Pelatnis (see fig. 15). Fourth Sub-order. Ophidii Viperifonnes. Viperine snakes. Maxillary very short, capable of rotation in its transverse axis, and armed with a single long tooth, which is perforated. Viviparous. Family 1. VIPEKIDJE (Vipers). Loreal region flat, without pit. Old World genera : Vipcra, Cerastes, Daboia, Echis (see fig. 17), Athcris. Australian : Acanthophis. Family 2. CROTALID.E (Pit Vipers, Rattlesnakes). Loreal region with a pit. Old World genera : ffalys, HypnaU, Trimcresurus (see fig. 18), Calloselasma, Peltoj)clor. New World genera : Cenchris, Bolh- rops, Botkriopsis, Bothricchis (Rhijwceroj)hw), Atropos, Tri- gonocephalus, Lachesis, Crotalophorus, Crotalus (see fig. 16). This list, from which many genera or sub-genera that are not well defined have been excluded, will give an idea of the great variety of forms by which the Ophidian type is represented at the present period. Additions, more or less numerous, are made to it every year; but the Typhlopsbothriorlti/arlitis. from India. discoveries of late years have not revealed any new im- portant modifications of structure, but rather have under- mined the distinctions hitherto made be- tween genera, groups, and families, so that it would appear as if we were acquainted with all the principal forms of snakes now living. We have now to add some notes on snakes to which special interest is attached, or which are most frequently brought to the notice of v^/ the observer or reader. The snakes most^M, remote from the true Ophidian type are the ' ' members of the first family, Typhlopidse. They are a small degraded form, adapted for burrowing and leading a subterranean life like worms. Their body is cylindrical, rigid, covered with smooth, short, highly polished, and closely fitting scales, without broad ven- tral scutes; tail very short; head joined to the trunk without neck-like constriction behind, and short, rounded, or with an acute rostral F shield, the principal instrument for bur- rowing in loose soil or mould. Their eye is quite rudimentary and can only give them a general perception of light. Their mouth is narrow, small, armed with but a few teeth in one of the jaws, and not distensible, allowing them only to feed on very small XXII. 25 7. Three minus (India), magnified.