208 THE AMERICAN NATURALIST [Vol. LII 



the last one or two caudal vertebrae are commonly rudi- 

 mentary, so much so that it is not always easy to deter- 

 mine their exact number. It is scarcely more fitting to 

 apply the term "meristic variation" here than it would 

 be to apply this term to such variations in the number of 

 cells as distinguish a larger from a smaller foot or ear. 



(To he concluded.) 



