V0l 19Cm m ] Stejneger, Isolation vs. Natural Selection. 265 



things about the natural history of the islands which coincide in 

 detail with my own observations. 



Professor Chas. F. Holder, an authority on the natural history 

 and ethnology of the California coast islands, believes the quail to 

 be native on Catalina Island. He assures me (in a letter dated 

 April 8, 1906) of their constant abundance there from the time of 

 his first acquaintance with the island 21 years ago. 



Therefore the characters of Lophortyx catalinensis , as here 

 pointed out, appear to be significant of long isolation, rather than 

 of acquisition within a few years. 

 Pasadena, California. 



ISOLATION VERSUS NATURAL SELECTION. 



BY LEONHARD STEJNEGER. 



In a recent paper in 'The Auk' (XXIII, April, 1906, pp. 161-171) 

 Mr. Hubert O. Jenkins has given a very instructive account of the 

 * Variation in the Hairy Woodpecker (Dryobates villosus and sub- 

 species)', accompanied (p. 163) by a map of the geographical dis- 

 tribution of the various subspecies recognized by him. 



In looking at the map I was forcibly struck by the fact that the 

 boundaries of the various forms do not coincide with those of the 

 various ' life zones ' commonly recognized by North American 

 zoologists. The nearest approach to such a coincidence is the 

 range of Dryobates villosus leucomelas and the so-called boreal zone. 

 In the United States the other subspecies show a certain agreement 

 with the two main east and west divisions of the transcontinental 

 belts, the humid and the arid divisions of the transition, upper 

 austral and lower austral life zones. It is a curious fact, however, 

 that while the zoologists do not recognize an east and west division 

 of the boreal belt, the distribution of the woodpeckers in question 

 clearly indicates that the Pacific slope of the continent included in 

 the boreal zone has some forms as markedly separated from the 

 eastern forms as those further south. 



