f )4 VERTEBRAE AND JAWS OF SNAKES. 



abdomen would have no hold of the yielding element, their movements are always of this 

 undulatory description. The number of vertebra?, and consequently of ribs, varies much in 

 different species, in some Snakes being about three hundred. 



The jaws of the serpents are very wonderful examples of animal mechanics, and may be 

 cited among the innumerable instances where the existing construction of living beings has 

 lono- preceded the inventions of man. We have already seen the invaluable mechanic inven- 

 tion of the ball-and-socket joint exhibited in the vertebrae of the Snakes, and it may be men- 

 tioned that in the spot where the limbs of almost all animals, man included, are joined to 

 the trunk, the ball-and-socket principle is employed, though in a less perfect manner than 

 in the Snakes. It is by means of this beautiful form of joint that posture-masters and 

 mountebanks are able to contort their bodies and limbs into so many wonderful shapes, the 

 muscles and tendons yielding by constant use and enabling the bones to work in their sockets 

 without hindrance. Indeed, a master of the art of posturing is really an useful member of 

 society, at all events to the eye of the physiologist, as showing the perfection of the human 

 form, and the wonderful capabilities of man, even when considered from the mere animal 

 point of view. 



In the jaw of the serpents, we shall find more than one curious example of the manner 

 in which human inventions have succeeded, if, indeed, they have not been borrowed from 

 some animal structure. 



All the Snakes are well supplied with teeth ; but their number, form, and structure differ 

 considerably in the various species. Those Snakes that are not possessed of venomous fangs 

 have the bones of the palate as well as the jaws furnished with teeth, which are of moderate 

 size, simple in form, and all point backward, so as to prevent any animal from escaping 

 which has ever been grasped, and acting as valves which permit of motion in one direction- 

 only. 



The bones of the jaw are, as has already been mentioned, very loosely constructed, their 

 different portions being separable, and giving way when the creature exerts its wonderful 

 powers of swallowing. The great python Snakes are well known to swallow animals of great 

 proportionate size, and anyone may witness the singular process by taking a common field 

 Snake, keeping it without food for a, month or so, and then giving it a, large frog. As it 

 seizes its prey, the idea of getting so stout an animal down that slender neck and through 

 those little jaws appears too absurd to be entertained for a moment, and even the leg which it- 

 has grasped appears to be several times too large to be passed through the throat. But by slow 

 degrees the frog disappears, the mouth of the Snake gradually widening, until the bones sepa- 

 rate from each other to some distance, and are only held by the ligaments, and the whole jaw 

 becoming dislocated, until the head and neck of the Snake look as if the skin had been 

 stripped from the reptile, spread thin and fiat, and drawn like a glove over the frog. 



No sooner, however, has the frog fairly descended into the stomach, than the head begins 

 to assume its former appearance ; the elastic ligaments contract and draw the bones into their 

 places, the scales, which had been far separated from each other, resume their ordinary posi- 

 tion, and no one woidd imagine, from looking at the reptile, to what extent the jaws and neck 

 have recently been distended. As many of the Snakes swallow their prey alive— the frog, for 

 example, having been heard to squeak while in the stomach of its destroyer— the struggles of 

 the internal victim would often cause its escape, were it not for the array of recurved teeth, 

 which act so effectually, that even if the Snake wished to disgorge its prey it could not do so. 

 Mr. Bell had in his collection a small Snake which had tried to swallow a mouse too large even 

 for the expansile powers of a Snake's throat, and which had literally burst through the skin 

 and muscles of the neck. 



The lower jaw, moreover, is not jointed directly to the skull, but to a most singular 

 development of the temporal bone, which throws out two elongated processes at right angles 

 with each other, like the letter [_ laid horizontally "1, so that a curious double lever is 

 obtained, precisely after the fashion of the well-known " throwing-stick " of the aboriginal 

 Australians, which enables those savages to tiing their spears with deadly effect to a distance 

 of a hundred yards. 



