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THE AMERICAN NATURALIST [Vol. XLVII1 



type is not so great as to arouse antagonism against the 

 varying individual on the part of others of its species. 

 Also, the gradualness of the change allows the species to 

 become accommodated to any disadvantage that might 

 concomitantly arise. 



8. The converse of this centripetal style of pigmenta- 

 tion is present in many species, and results in pigmenta- 

 tion (commonly black) at the extremities or along lines 

 where primary breaks occur in the centripetal form, 

 namely at the tip of the nose, ears, tip of the tail or the 

 toes; possibly the black dorsal stripe is due also to centri- 

 fugal pigmentation. Patterns may develop as in certain 

 antelopes by a white break between patches of the two 

 types. 



In conclusion, I wish to express my indebtedness to 

 Professor W. E. Castle for much helpful criticism and 

 advice, and to the Museum of Comparative Zoology for 

 permission to make record of specimens in its study 

 collection. 



REFERENCES 



Allen, G. M. 



1904. The Heredity of Coat Color in Mice. Prod Amer. Acad. Arts and 

 Sci., Vol. 40, pp. 61-163. 



