CLASS III. REPTILIA 



ORDER 4. OPHIDIA. 



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locomotion: they can creep, glide, grasp, suspend themselves, erect themselves, leap, dart, 

 bound, swim, and dive. They are mostly oviparous, their eggs being soft, of a yellowish-white 

 color, covered with a leathery skin, and from twenty to thirty in number at each laying. 

 Their senses are not very acute ; the eyes are small, and without lids ; the tongue is free, forked, 

 and capable of considerable elongation and rapid motion. They are divided by Dr. Gray into 

 two sub-orders, the Viperina, or Venomous Serpents, and the Colubrina, or Colubrine Snakes, 

 which are for the most part harmless, though some of them are otherwise. These animals are 

 exceedingly numerous, no less than one hundred and fifty species being in the Catalogue of the 

 British Museum. We shall only attempt to describe a few of the most remarkable kinds. 



THE VIPERmA. 



The Viperina, so far as known, are all ovo-viviparous ; they are also distinguished by the pecu- 

 liar arrangement of the teeth in the upper jaw. The true maxillary bones are reduced to a very 



small size, capable of a great amount 

 of motion, and bear a single pair of long 

 curved fangs, which can be laid flat in 

 the mouth during repose, or erected 

 when in action by the agency of pecu- 

 liar muscles. These are the only teeth 

 supported by the maxillary bones ; 

 they are perforated throughout by a 

 slender canal, which communicates with 

 a large gland situated in the head, be- 

 hind and under the eyes. This secretes 

 the venomous fluid,which passes through 

 a duct to the base of the tooth, and 

 thence through, the canal in its interior, 

 until it is injected into the wound made 

 by the bite of the serpent. Its propulsion is effected partly by the contraction of the proper walls 

 of the gland, and partly by the pressure of the muscles of the jaws, which act upon it during their 

 contraction. The poison which is thus injected into the wound mixes with the blood, and is then 

 carried into the circulation, where it speedily produces an injurious effect, giving rise to an altered 

 condition of the blood, which, if the poison be present in sufficient quantity, quickly renders it 

 incapable of supporting life. In fact, a bite from one of the large poisonous snakes of tropical 

 climates is generally fatal, even to man, if the animal be in a vigorous condition, and provided 

 with a good supply of poison ; but a bite from a similar snake, after it has nearly exhausted its 

 venom by previous attacks, may give rise to little or no inconvenience. It is remarkable, also, 

 that the effect of the poison of these creatures is very different upon different animals ; the cold- 

 blooded species in general appear to be almost indifferent to its effects, while most warm-blooded 

 animals soon expire when a sufficient quantity is injected into their veins. Various means of 

 preventing the injurious effects of the bite of these reptiles have been proposed, and the natives 

 of most countries in which they abound have their favorite antidotes for the wounds inflicted by 

 them. The only means, however, upon which it appears that much reliance can be placed, are 



SECTION OP THE HKAD OP A SERPENT. 



a, poison fangs; b, poison glands; c, conductor for the poison ; d d, 

 muscles of the jaws; e, tendon of the muscles; s, salivary glands. 



