452 SCIENCE PROGRESS. 



tween the three normal and four abnormal premolars of A teles 

 (49) and the three sides of an equilateral triangle and the 

 four sides of a square appears to me a little fanciful and pre- 

 mature, as I think it almost certain that when we examine 

 the development of the teeth in that form we shall find that 

 the germs of four premolars are invariably laid down, and 

 that a definite one (retained in this abnormal specimen) 

 always degenerates. 



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