558 



REPTILE. 



ing or masticating: one, is of course constructed in all | 

 its parts for the work which it performs, and being 

 so, tends to disqualify it for performing the opposite 

 kind of work. The under ja\v, as in birds, is made 

 up of two maxillary bones ; and these are not articu- 

 lated upon the bones of the head as in the mammalia, 

 or on the upper jaw as in the crocodile, but upon an 

 intermediate bone on each side, resembling' the os 

 quadratum in birds, both in situation and in use. 

 The union of the upper jaw with the cranium, though 

 not an articulation, is very loose in all the species ; 

 and, in some of those that swallow large prey, it has 

 nearly all the flexibility of a Joint; and, as the ten- 

 dinous or lieamentary connexion is flexible every 

 way, even this jaw is capable of twisting motions. 

 This flexibility at the junction of the upper jaw with 

 the cranium may be considered as serving fully as 

 much in removing the skull and its contents out of 

 the way of any very large prey which the animal 

 may have to swallow, as in merely widening the 

 gape, for which the organisation of the jaws them- 

 selves is abundantly sufficient. In the most remark- 

 able of the swallowing serpents, the great python of 

 south-eastern Asia and its isles, the mastoid extends 

 backwards very considerably in rear of the articula- 

 tion of the head with the neck, and to such a distance 

 that there is twice as much length behind the orbit 

 of the eye as there is between that and the inter- 

 maxillary bone at the point of the muzzle. To the 

 under side of the extremity of the mastoid, the os 

 quadratum, or trunk bone (caisse), is articulated, the 

 articulation being on the same part in the orbit, when 

 the jaws are in a state of repose. In this state the 

 os quadratum stands in a perpendicular direction, and 

 the lower jaw is articulated to its under extremity. 

 The bone is not so long in proportion in the python 

 as in some other serpents, but it is, and indeed all the 

 bones of the mouth and jaws are, very strong. Each 

 jaw may thus be said to be articulated upon one 

 extremity of this connecting bone, so that while the 

 lower one opens forward or downward upon it, the 

 upper one moves forward and upward. The opening 

 of the mouth is therefore extended to the full measure 

 of both jaws, together with the two connecting bones, 

 which furnishes a gape of very large dimensions. 

 About one-half of this vast circumference is margined 

 with very powerful conical teeth, considerably bent 

 backwards and a little inwards, but with the short 

 points a little round, so that they the more readily 

 take hold of any substance. In the lower jaw there 

 is only one row of these teeth, but in the upper there 

 are teeth on various parts. There are four small 

 ones on the intermaxillary bone ; fourteen in each 

 side, in the external row in the maxillary, and three 

 small ones in the anterior part within these, as a 

 second row. Then there are six on each of the 

 palatal bones, and eight on each of the pterygoids, 

 forming a continuation which reaches very nearly to 

 the opening of the gullet, which opening can be ex- 

 tended to the full width opened by the circle of bones 

 in the mouth, when brought to a plane, which is of 

 course the position in which they form the most 

 ample circumference. There are thus altogether one 

 hundred and four teeth in the upper jaw, and there 

 are thirty-six in the lower, making in all one hundred 

 and forty teeth, and teeth of a very formidable cha- 

 racter in the way in which they are intended to act, 

 in the mouth of this mighty monarch of the pestilent 

 swamps of the oriental isles. Of its other power, 



that of crushing very strong animals in its folds, we 

 shall speak afterwards. 



In those serpents which kill by poisoning, the me- 

 chanical armature of the mouth is of a less formidable 

 character, though in them also the gape is of large 

 dimensions for the size of the animal. The rattle- 

 snake will serve as an illustration of these. The 

 mastoid is rhuch smaller than in the python, and the 

 articulation of the os quadratum is not farther back 

 than that of the head. That bone is long and slen- 

 der, and in a state of repose inclines backward at its 

 lower extremity. The under jaw is longer than the 

 upper, and considerably bent, with the concavity 

 upwards. The palatal and pterygoid bones of the 

 upper jaw are bent in the contrary direction. 



The only teeth which appear fully developed in 

 the upper maxillary bones are the poison-fangs, one 

 on each side near the anterior part of the bone ; but 

 there are others behind them, at least in some cases, 

 which could take the place of those in the event of 

 their being broken or lost ; these are hollow, with 

 openings near the points, from which the poison is 

 discharged. When the animal is in a state of repose 

 these deadly weapons are concealed in folds of the 

 integument. They are not, however, folded down 

 by an articulation on the maxillary, for they are firmly 

 set in that bone, and indeed could not act so well 

 were they jointed at their roots. The short maxilla- 

 ries in which they are inserted have a motion on the 

 transverses ; and two muscles, which have their 

 origin on the other bones of the jaw a considerable 

 way backwards, are inserted into the upper part of 

 the maxillary, so that when they contract they turn 

 the bone by pulling the upper part of it, and the ad- 

 vance which this causes elevates the poison teeth, or 

 fangs as they are called. The same muscles pass 

 one on each side of the poison bags, and compress 

 them at the same time that they elevate the fangs. 

 The pulling back of the upper part of the head of 

 the bone also shortens the poison duct, and thus 

 enables it to give way, by an enlarged diameter, to 

 the passage of the virus, thus these serpents always 

 infuse their poison into any wound which they make 

 with their fangs, as the very same muscular apparatus 

 works both the fang and the poison. The transversal 

 bones, which are very long in these animals, have a 

 bend upwards, so that they are out of the way of the 

 poison apparatus : and the bend downwards of the 

 palatal bone at the middle part conduces to the same 

 purpose, by preventing any thing against which the 

 roof of the mouth may press from interrupting the 

 flow of the poison. The increased depth necessary 

 in the anterior part of the maxillary, for allowing the 

 fangs to be lowered and raised, gives more apparent 

 size to the muzzle in the poisonous serpents than is 

 possessed by those which are not poisonous. The 

 swallowing teeth of these serpents are few and of small 

 size, as compared with those of the species which 

 have no poisoning apparatus. They in general con- 

 sist of a single row of small teeth on each side of the 

 lower jaw toward the front, and another row on each 

 of the palatal bones ; but there arc none on the 

 intermaxillaries or the pterygoids ; and, with the 

 exception of the poison fangs, the mouth is not a 

 formidable one, either in the strength of its bones, or 

 the number, size, and character of the teeth with 

 which it is armed. 



A question has sometimes been raised as to the 

 use of these poison-fangs iu the economy of the ser- 



