ORDER OPHIDIA. 299 



entire length of the lower part of the same os quadratum, and 

 terminates at the hindermost apophysis of the branch of the 

 jaw, just beyond its articulation. 



It is easy to conceive that the first two of these muscles 

 tend to approximate the jaws to each other, and to close the 

 throat. 



Those which act upon the upper jaw are more numerous. 

 One of them, very fleshy, springs from the capsule, which 

 surrounds the articulation of the jaw along with the os qua- 

 dratum^ and spreads over the purse of the venomous teeth, 

 and over the posterior apophysis of the maxillary bone, so 

 that in contracting it must carry down the fangs when they 

 are upright. Two others, directed in an inverse way, are 

 situated between the middle line of the base of the cranium, 

 and the palatine arches. The first, subcutaneous, occasions 

 the protraction of the maxillary bone, or the raising of the 

 fangs and the narrowing of the mouth, by the approximation 

 of the two interior arches. The second, more slender, and 

 situated above it, is destined to draw back the entire mass of 

 the upper jaw, producing at the same time the approximation 

 of the two branches which form it. Thus, in biting any 

 body, the serpents can twist the mouth, at the same time 

 that they dilate it beyond measure. 



All the ophidians have the mouth furnished with teeth, 

 but these teeth do not serve for the purposes of mastication. 

 They are only fit for the retention of prey. The muscles in- 

 tended for moving the osseous frame- work which supports 

 them, cannot perform the operation of grinding. The only 

 faculties they possess, are those of raising, of lowering, of 

 separating, of approximating, and of carrying backwards and 

 forwards. 



The tissue of the teeth presents nothing very peculiar. 

 The osseous portion is hard and compact. The enamel is of 

 no great thickness, and no cement is ever observed in their 



