SERPENTS. 385 



o]ilii<lians. Tho clongafcil l)oily, tlinnj^h sii1>-fylin<lrical anteriorly, is jifiRtoriorly com- 

 pressed, the tail often beintj sha])cd like a brr)a<l jiadillo. To brini; about this struc- 

 ture, the caudal vertel)rie are coinitressed, and their vertical jtrocesses eloiij^ated. Tho 

 head is rather 'indistinct' in most of the forms, and bears the valvular nostrils, ex- 

 cept in Platurua, on the u|)])or side; the eyes are small, with a ro\nid jnipil ; there is 

 no loreal j)late, and the general scutellation of the head is regular; the body scales 

 are small, and may b(! keeled or tuljerculate ; the fangs are of ordinary size, erect and 

 grooved, and followed by other teeth of simple structure. 'J'lie members of the 

 family inhabit the tro])ical portions of the Indian and Pacific oceans, and sometimes 

 enter fresh water. All are ))urely aquatic, spending their whole life in the water, out 

 of which they appear to Im; blind an<l soon die {Platurus may be an exception to this 

 statement, as it offers many structural characters o])])osed to the other Ilydrojdiida;). 

 In their general form the sea-snakes arc most admirably adapted for their acpiatic life. 

 The compressed body and ])addle-like tail not only jioint to this, but the belly is not 

 rounded as in other o])hidians, but sharji, like that of a heri'ing. The ventral scutes, 

 moreover, not being of value for aquatic locomotion, are not specialized, or, if so, only 

 in a mild degree. The tail, though sha|)ed like that of a fish, is at the; s.aine time pre- 

 hensile, enabling the animal to I'est by winding it about some half-sidimerged root or 

 piece of coral. The nostrils are so jirovided with valves, that when the enormous 

 lungs have been inflated, they can In; tightly closed, and the animal, with its sujijily of 

 air, can either dive below the surface or rest motionless, being buoyed up by having 

 its siiecific gravity tlius diminished. Tho position of the nostrils is such as to enable 

 them to breathe without ])rolruding more than the tip of the snout from the water. 

 The armament of scales has been seized u])oa by the naturalist as offering a means of 

 classifying the several sj)ecies. While a fttw iiave the scales imbricated, like those of 

 terrestrial serpents, the majority have them merely jiixtajiosed, and often lose their 

 horny covering and become tuljercular and soft. The shields of the head (excej)! in 

 Platurus, which form is generally exce])tional), are so changod as to often lose all 

 resemblance to those of ordinary o])hidiaiis. In shedding their epidermis, the sea- 

 snakes resemble the lizards, only a small jtortion being exuviated at a time. The eye 

 of the sea-snake is so weak that, when the animal is taken from the water, all its at- 

 tempts tf) strike prove ineffectual. The mouth is so closed l)y a development of the 

 rostral plate, as to ordinarily prevent the entrance of water, though in some forms there 

 are two small ojjenings for the extrusion of the bifurcated tongue. The family Jjos- 

 sess poison of the most intense virulence, by which they obtain their food, which 

 consists exclusively of fishes. These they seize and sting, tho poison .affecting the 

 unforttuiate animal so that it almost instantly dies, and in a relaxed condition, so that 

 till! serjient, in swallowing them, as it does, head first, has no inconvenience from the 

 otherwise erect ami rigid spines and barbs with which many ])elagic fishes are arme(l. 

 Though naturally shy, the sea-snake will, when attacked in its native element, dart 

 at the intruder with all the vigor of the indignant terrestrial forms ; but when drawn 

 up in nets they are apparently helpless, the fishermen picking them up and throwing 

 them back into the water with the most surjirising unconcern. 3Iany experiments 

 have been made to keep the sea-snakes in aquaria, but they invariably die in :i few 

 days. All the fomis are viviparous, the young, sometimes to the number of nine, being 

 active swimmers from the first. The ailult males may be easily distinguished from 

 the females, as they have on each side of the tail an area which seems to be consider- 

 ably swollen. The natural enemies of the searsnakes are the eagle-rays and rapacious 

 VOL. III. — 25 



