562 



REPTILE. 



distinctions as to these scaly appendages, which are 

 accompanied with differences both in the characters 

 of the animals and the styles of their locomotion. 

 Those which have the same kind of scales upon the 

 upper and the under part of the body, may all be 

 considered as quite harmless ; and, unless to the very 

 small prey on which they feed, they are among- the 

 most innocent and gentle of all living creatures. In 

 those the ossa-quadrata are articulated immediately 

 upon the cranium, without the intervention of mas- 

 toid bones ; and the upper maxillaries are united to 

 the cranium and the intermaxillaries, so that the width 

 of their gape is limited. Their ribs also do not in 

 any way act as legs, so that their progressive motion 

 is performed by flexures of the body. They are 

 quick and gliding in their motions, and can in general 

 move with either end foremost. They advance into 

 higher, latitudes than the others. They are not in 

 fact true serpents, but snakes ; and they ought not to 

 share any part of the suspicion which attaches to the 

 others. The hard coverings of their bodies are true 

 scales. Some of them have a third eyelid like the 

 Sauria, and slight rudimental traces of scapulars and 

 clavicles, though not even a vestige of anterior ex- 

 tremities. 



The true scales upon all serpents are placed 

 lengthways, and pointed or rounded at their posterior 

 extremities, in which they differ from the scuta or 

 shields which are on the under part of the true ser- 

 pents. These are placed crossways on the belly, and 

 attached at the ends to the two ribs, which are arti- 

 culated on the same vertebra, as already noticed. 

 They are continued on the under side of the tail, 

 sometimes only in one row, and sometimes in two ; 

 and in all the species that have them, these shields 

 may be considered as answering the purposes of a 

 sort of feet. When these serpents move at their 

 full speed, they do it by forming the body into suc- 

 cessive arches, the scales behind the arch holding on 

 till the extending of the arch advances the fore part 

 of the body. In their slower marches they literally 

 creep along with hardly any flexure, and it is this 

 which forms their characteristic style of marching. 

 One of the actions of the muscles attached to the 

 ribs depresses the anterior part of the shield and 

 raises the posterior, so that it takes a hold on the 

 ground. By this mea,ns, also, the anterior edge 

 of each shield can get on below the posterior one 

 in advance of it, by which means smother mus- 

 cular action is enabled to shorten the distance 

 between shield and shield, over a considerable por- 

 tion of the under side of the animal. The more that 

 the distance is shortened, the more the posterior 

 edges of the shields are raised, and they take the 

 firmer hold of the surface over which the animal 

 moves. Thus, by holding on with the hind part 

 while the fore part is advanced, this curipus method 

 of walking by means of ribs and shields, instead of 

 legs and feet, is carried on with great ease, and much 

 mare rapidly than one who had not seen, it would be 

 apt to suppose. When the fore part of the body is to be 

 advanced, the oblique intercostal muscles pull the 

 ends of the shields upwards ; and when the length of 

 the under part is to be contracted in order to bring 

 up the rear of the animal, the muscles, which extend 

 parallel to the axis of the spine, draw the ribs to- 

 gether. The celerity with which this creeping motion 

 is performed is much more considerable than those 

 who are in the habit, of associating locomotion 011 the 



earth with feet only would be ready to believe ; and 

 t affords a proof of a very general and very 'delight- 

 ill principle in the working of nature, namely, that 

 t is of very little consequence what form of organ 

 is provided for any particular purpose ; for, be the 

 organ what it may, the labour is always sure to be 

 done in the best manner, and with the minimum of 

 exertion on the part of the animal. 



The whole of the Ophidia can swim, although some 

 take the water more readily than others ; and there are 

 several that live habitually in it. There is, however, 

 no ophidian reptile that is furnished with gills, and 

 entitled, as so furnished, to be called an aquatic ani- 

 mal. Their mode of swimming is by flexures of the 

 body, which are chiefly performed in the vertical 

 plane, or in the cross direction to those of the eel ; 

 and, as they have no fins of any kind, this is an 

 advantage to them, as it enables them to ascend and 

 descend by the flexures of the body alone, which 

 they could not do if the flexures were lateral, unless 

 they were possessed of lateral fins to serve them as 

 means of support. 



Considered in its mechanical structure, the ali- 

 mentary apparatus of all the Opkidia is very simple ; 

 and the process of digestion depends upon the solvent 

 power of the gastric juice, and very little on the ac- 

 tion of the vessels. The gullet and stomach, in the 

 serpents of large gape especially, have far more capa- 

 city of distension than those of any other animals, 

 the wide-mouthed fishes not excepted. The stomach 

 is little else than an enlargement of the gullet ; and 

 both have a solvent power. This is necessary, if, 

 as it is said, the great crawling serpents swallow a 

 deer, all to the horns, which continue sticking out 

 from the sides of the gape, until the solution of the 

 body has proceeded so far that they drop off. 



The organs of circulation and breathing are also 

 simple. The heart has two auricles and one ven- 

 tricle, and only a portion of that which returns from 

 the systematic circulation, is sent to the lungs. These 

 lungs consist of a single sac, having large cells on its 

 walls, and being situated in the cavity of the abdomen. 

 The windpipe and the larynx are membranous ; and 

 thus the animals have no voice but hissing, which 

 is produced by the passage of the expired air through 

 the opening of the larynx, without any action of the 

 membranes of that organ. The hiss accompanies ex- 

 citement, and corroborates what we have said of the 

 increase of respiration being necessary to work up the 

 system of the animal to its full heat. In their pro- 

 duction some are oviparous, and some ovoviviparous ; 

 those which have the former habit are more prolific, 

 and consist of most of the harmless serpents ; and 

 those which have the last are less prolific, and belong 

 chiefly to the true serpents. 



Ophidia are all creatures of wild nature, for which 

 there does not appear to be much place or use after 

 man begins to cultivate extensively. They accord- 

 ingly disappear before the progress of improve- 

 ment, the dangerous ones first, and the others after- 

 wards. Many of the savage tribes eat their flesh, 

 which is said to be wholesome and nutritious ; and 

 there was a time when feeding upon the flesh of 

 vipers was considered as one of the best means of j ire- 

 serving and increasing female beauty. It is said that, 

 when man began to eat turtle in those parts of the 

 world, women ceased to eat vipers; but whether this 

 did or did not arise from their despairing of carry- 

 iug on the war successfully with the luxuries of 



