THE BOA CONSTRICTOR. 511 



Ou removiug the lower jaw the two fangs are seen in the upper jaw, 

 folded down in a kind of groove between the teeth of the palate and 

 the skin of the head, so as to allow any food to slide over them with- 

 out being pierced by their points. The end of the teeth reach about 

 halfway from the nose to the angle of the jaw, just behind the corner 

 of the eye. 



Only the tips of the fangs are seen, and they glisten bright, smooth, 

 and translucent, as if they were curved needles made from isinglass, 

 and almost as fine as a bee's sting. On raising them with a needle or 

 the point of the forceps, a large mass of muscular tissue comes into 

 view, enveloping the tooth for the greater part of its length, and being, 

 in fact, the means by which the fang is elevated or depressed. When 

 the creature draws back its head and opens its mouth to strike, the de- 

 pressing muscles are relaxed, the opposite series are contracted, and 

 the two deadly fangs spring up with their points ready for action. It 

 is needful to be exceedingly careful while dissecting the head, as the 

 fangs are so sharp that they penetrate the skin with a very slight touch, 

 and their poisonous distilment does not lose its potency even after the 

 lapse of time. 



There are generally several of the fangs in each jaw, lying one be- 

 low the other in regular succession. From the specimen which has 

 just been described I removed four teeth on each side, varying in length 

 from half to one-eighth the dimensions of the poison-fangs. 



The ordinary food of the Viper is much the same as that of the com- 

 mon snake, and consists of mice, birds, frogs, and similar creatures. It 

 is, however, less partial to frogs than is the common snake, and seems 

 to prefer the smaller mammalia to any other prey. 



We now arrive at a very important family of serpents, including the 

 largest species found in the order. These snakes are known by the 

 popular title of Boas, and scientifically as Boidse, and are all remark- 

 able, not only for their great size and curious mode of taking their 

 prey, but for the partial development of their hinder limbs, which are 

 externally visible as a pair of horny spurs, set one on each side of the 

 base of the tail, and moderately well developed under the skin, con- 

 sisting of several bones jointed together. 



The Boa Constrictor is a native of southern and tropical America, 

 and is one of those serpents that were formerly held sacred and wor- 

 shipped with divine honors. It attains a very large size, often exceed- 

 ing twenty feet in length, and being said to reach thirty feet in some 

 cases. It is worthy of mention that before swallowing their prey the 

 Boas do not cover it with saliva, as has been asserted. Indeed, the 

 very narrow and slender forked tongue of the serpent is about the 

 worst possible implement for such a purpose. A very large amount 

 of this substance is certainly secreted by the reptile while in the act 



