THE 



AMERICAN NATURALIST 



THE EFFECT OF EXTENT OF DISTRIBUTION 

 ON SPECIATION 



ASA C. CHANDLER 

 CONTENTS 



3. Test of Theory by Comparison of' Fauni 



Amphipoda 

 ConsM* r.iUnn- 

 Isolation . 



Time J 

 Differe 

 5. TheorPtic 



While engaged in some research work on the geo- 

 graphic distribution of mammals under the supervision 

 of Professor H. D. Reed at Cornell University in the fall 

 of 1910 and the spring of 1911, certain conceptions re- 

 garding the relation between extent of distribution and 

 the generic and specific modifications of mammals were 

 brought to light. Due to the valuable and helpful criti- 

 cism of Professors C. A. Kofoid and J. C. Merriam, and 

 Dr. J. Grinnell, and of other members of the University 

 of California, and to the advice and aid of Professor 

 C. A. Kofoid, the rather vague ideas then formed have 

 been worked over and crystallized into their form as 

 Presented in this paper. 



