DENTITION. 345 



accident has broken off the old ones, but they are all shed at 

 more or less regular intervals, coinciding with the casting of 

 the epidermis.' Not on each occasion of sloughing, as we 

 may, I think, understand this, but, like the casting of cuticle, 

 contingently, according to the condition of the individual. 

 Not altogether, either, or at certain periods of life, as a child 

 loses his first teeth and gets a second crop, or as an adult cuts 

 his wisdom teeth, but ' a crop of young teeth work their 

 way into the intervals of the old teeth, and gradually expel 

 these latter.' All the spaces and depressions between the 

 maxillary and palatine rows are occupied by the matrix of 

 tooth germs. Not a cut can be made in this part of the 

 palate without the knife turning up a number of young 

 teeth in every stage of development.^ 



Independently of this accidental number, the maxillary 

 presents certain phases which characterize families. For 

 instance, a true viperine snake has in the upper jaw fangs 

 only : non-venomous snakes have a whole row of from fifteen 

 to twenty-five maxillary teeth, and in intermediate species 

 their normal numbers vary considerably. Some of the 

 highly poisonous families, notably the cobras and the sea 

 snakes, have a few simple teeth in addition to fangs. The 

 length of the jaw, therefore, diminishes in proportion to the 

 number of teeth it bears. Only the viperine snakes 

 are limited to the poison fang in the upper jaw ; but 

 fangs, like the simple teeth, are shed, broken, or lost, and 

 renewed continually. 



Behind the one in use — the functional fang — others in 

 various stages of development are found — ' a perfect store- 



"^ Indian Snakes, by Ed. Nicholson, M.D, Madras, 1S70. 



