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THE AMERICAN NATURALIST [Vol. XLVI 



teeth of the mule ; this may be partly connected with the 

 mesohlastic derivation of the dentine of the teeth. 



Monophyletic 



Mesohlastic derivatives, on the other hand, are divided 

 between the sire and dam, the skeleton and limbs of the 

 mule being mainly proportioned as in the ass, while the 

 skull of the mule, as we shall see, is almost purely that 

 of the horse. 



Blended and Pure Inheritance in the Bones of the Face 

 Blending. — A comparison of the bones of the side of 



