410 



HISTORY OF FROGS, LIZARDS, AND SERPENTS. 



Like most other animals, serpents are fur- 

 nished with lungs, which, I suppose, are ser- 

 viceable in breathing, though we cannot per- 

 ceive the manner in which this operation is 

 performed; for though serpents are often seen, 

 apparently, to draw in their breath, yet we 

 cannot find the smallest signs of their ever re- 

 spiring it again. Their lungs, however, are 

 long and large, and doubtless are necessary to 

 promote their languid circulation. The heart is 

 formed as in the tortoise, the frog, and the lizard 

 kinds, so as to work without the assistance of 

 the lungs. It is single, the greatest part of 

 the blood flowing from the great vein to the 

 great artery by the shortest course. By this 

 contrivance of nature we easily gather two 

 consequences that snakes are amphibious, 

 being equally capable of living on land and in 

 the water; and that also they are torpid in 

 winter, like the bat, the lizard, and other ani- 

 mals formed in the same manner. 



The vent in these animals serves for the 

 emission of the urine and the fasces, and for 

 the purposes of generation. The instrument 

 of generation in the male is double, being 

 forked like the tongue ; the ovaries in the fe- 

 male are double also ; and the aperture is very 

 large, in order to receive the double instrument 

 of the male. They copulate in their retreats: 

 and it is said by the ancients, that, in this si- 

 tuation, they appear like one serpent with two 

 heads : but how far this remark is founded in 

 truth, I do not find any of the moderns that 

 can resolve me. 



As the body of this animal is long, slender, 

 and capable of bending in every direction, the 

 number of joints in the back-bone are numer- 

 ous beyond what one would imagine. In the 

 generality of quadrupeds, they amount to not 

 above thirty or forty ; in the serpent kind they 

 amount to a hundred and forty-five from the 

 head to the vent, and twenty-five more from 

 that to the tail. 1 The number of these joints 

 must give the back-bone a surprising degree 

 of pliancy ; but this is still increased by the 

 manner in which each of these joints are locked 

 into the other. In man and quadrupeds, the 

 flat surfaces of the bones are laid one against 

 the other, and bound tight by sinews: but in 

 serpents, the bones play one within the other, 

 like ball and socket, so that they have full 

 motion upon each other in every direction. 2 

 Thus, if a man were to form a machine com- 

 posed of so many joints as are found in the 

 back of a serpent, he would find it no easy 

 matter to give it such strength and pliancy at 

 the same time. The chain of a watch is but a 

 bungling piece of workmanship in comparison. 



Though the number of joints in the back- 

 bone is great, yet that of the ribs is still great- 



1 Vide CKarat. Anatom. 



Derham, p. 390. 



er ; for, from the head to the vent there are 

 two ribs to every joint, which makes their, 

 number two hundred and ninety in all. These 

 ribs are furnished with muscles, four in num- 

 ber ; which being inserted into the head, run 

 along to the end of the tail, and give the ani- 

 mal great strength and agility in all its mo- 

 tions. 



The skin also contributes to its motions, 

 being composed of a number of scales, united 

 to each other by a transparent membrane, 

 which grows harder as it grows older, until 

 the animal changes, which is generally done 

 twice a year. This cover then bursts near the 

 head, and the serpent creeps from it, by an 

 undulatory motion, in a new skin, much more 

 vivid than the former. If the old slough be 

 then viewed, every scale will be distinctly 

 seen, like a piece of net- work, and will be 

 found greatest where the part of the body they 

 covered was largest. 



There is much geometrical neatness in the 

 disposal of the serpent's scales for assisting the 

 animal's sinuous motion. As the edges of the 

 foremost scales lie over the ends of their fol- 

 lowing scales, so those edges, when the scales 

 are erected, which the animal has a power of 

 doing in a small degree, catch in the ground, 

 like the nails in the wheel of a chariot, and so 

 promote and facilitate the animal's progressive 

 motion. The erecting these scales is by means 

 of a multitude of distinct muscles, with which 

 each is supplied, and one end of which is 

 tacked each to the middle of the foregoing. 



In some of the serpent kind there is the ex- 

 actest symmetry in these scales; in others, 

 they are disposed more irregularly. In some, 

 there are larger scales on the belly, and often 

 answering to the number of ribs ; in others, 

 however, the animal is without them. Upon 

 this slight difference Linnasus has founded his 

 distinctions of the various classes of the serpent 

 tribe. Human curiosity, however, and even 

 human interest, seem to plead for a very dif- 

 ferent method of distribution. It is not the 

 number of scales on a formidable animal's 

 belly, nor their magnitude or variety, that any 

 way excite our concern. The first question 

 that every man will naturally ask, when he 

 hears of a snake, is, whether it be large? the 

 second, whether it be venomous? In other 

 words, the strongest lines in the animal's his- 

 tory are those that first excite our attention ; 

 and these it is every historian's business to dis- 

 play. 



When we come to compare serpents with 

 each other, the first great distinction appears 

 in their size ; no other tribe of animals differ- 

 ing so widely in this particular. What, for 

 instance, can be so remotely separated as the 

 Great Liboya of Surinam, that grows to thirty- 

 six feet long ; and the Little Serpent, at the 



