300 CLASS REPTILIA. 



composition. In the non-venomous species the}'^ are conical, 

 curved, very pointed, directed backwards, and implanted 

 all along each of the maxillary, palatine, and mandibular 

 arches, on foiu- ranks in the upper jaw, and two only in the 

 lower. Their number, though always considerable, varies 

 very much. 



But in the venomous species, the maxillary branch bears 

 at its extremity but one hollow tooth, very long, and travers- 

 ed by a canal for the transmission of an empoisoned fluid, 

 which we shall treat of hereafter. Farther back this branch 

 contains several germs of analogous fangs, concealed in a 

 large pouch, which constitutes the gum. These are destined 

 to replace the visible tooth when it shall have fallen. We 

 find then, in the greatest part of the mouth but the two 

 ranges of palatine teeth, and the two ranges of the lower jaw, 

 and the fang itself, when the serpent does not think proper 

 to make use of it, remains concealed in a fold of the gum. 



By a natural consequence of the defect of mastication, the 

 salivary glands constitute a less important apparatus in the 

 organization of the ophidians than in that of the mammalia. 

 They are not, however, altogether wanting. It is even ob- 

 served, in some genera, as in those of the adders and boas, 

 that there are underneath the skin, along the external face of 

 the branches of the lower jaw, two elongated granulous 

 glands, the fluid from which is poured to the external side of 

 the correspondent teeth, and which, in the amphisboense, are 

 lodged immediately under the tongue between the genio-glos- 

 sal, and genio-hyoidean muscles. 



As for the glands which secrete the poison in most of the 

 heterodermatous serpents, they are found on the sides of each 

 branch of the upper jaw, behind the orbit, and almost below 

 the skin. Their tissue is granulated, like that of the salivary 

 glands, and two muscles, destined to raise the fangs, traverse 

 them from front to back, one outwards, the other under- 



