of the small burrowing snakes, has six rows of teeth. Of 

 these, two are on the maxillaries (and occasionally on their 

 posterior continuations the ectopterygoids), two run parallel 

 to these along their inner side, on the pterygo-palatine lines 

 of bones ; the other two are the mandibular teeth in the 

 lower jaw. 



The pterygopalatine row of teeth is always the longest, 

 the maxillary row is shorter. The former row may contain 

 from ten to thirty teeth, the latter from five to twenty or 

 more ; the mandibular row is nearly equal in number to the 

 maxillary. 



It is by no means easy to determine the number of teeth 

 possessed by a snake owing to their non-permanent charac- 

 ter and to the diificulty in distinguishing the new from 

 the old. 



Some snakes have teeth of equal or nearly equal size 

 (isodont) whilst in other kinds the teeth are irregular, or 

 gradually increase or decrease from before hindwards. A 

 very common form of dentition is for the teeth to increase 

 gradually and to terminate by a long tooth at the hinder 

 end of the maxilla (coryphodont.) 



These teeth are all directed more or less backwards, and 

 oppose a formidable obstacle to any resistance on the part 

 of prey once seized ; they are composed of a horny sub- 

 stance impregnated with bone-earth, formed originally on a 

 vascular centre, hollow in structure, and in the form of an 

 elongated cone, curved backwards at the base. 



Each tooth springs from a dental matrix in the bone, 

 protected externally by a mucous envelope; the greater 

 portion of the tooth is concealed by this envelope which is 

 however sufficiently loose to offer no resistance to the use of 

 the teeth. Inside this fold will be found a number of other 



