DENTITION, 367 



of these organs. ' Every relief on one surface fits into a 

 corresponding depression on the other surface, and accurate 

 apposition of every part is obtained,' Nicholson explains 

 to us. ' The four upper rows of teeth divide the roof into 

 three parts, and the lower jaw teeth fit between the upper 

 maxillary and palatine teeth.' 



There remains yet much more to describe in connection 

 with the poison fang, which might come in the present 

 chapter ; but as the two following will treat of the ViperidcE 

 and the Crotalidcs — the dentition being the same in both — 

 the viperine fangs shall claim further space under those 

 heads. These three consecutive chapters, and also chap, 

 xxii. on some exceptional forms of dentition, must neces- 

 sarily be somewhat blended ; but I divide them thus in 

 order to present the distinct families more clearly, and 

 render the subject less tedious to the reader. 



