Recentty published Ornithological Works. 507 



easily avoided. by deeper planting, is more than overbalanced 

 by the destruction for food, especially in the nesting season, 

 of large numbers o£ noxious insects. 



Chandler on Areas of Distribution and Extent of Specific 

 Modification. 



[The effect of extent of distribution or speciation. By Asa C. 

 Chandler. American Nat., xlviii. 1914, pp. 129-160.] 



This is an essay in which an attempt is made to show that, 

 as the range of a group of animals or birds is extended, the 

 number of species increase out of proportion to the genera, 

 and the genera out of proportion to the families. 



This thesis is tested by the author in a series of tables 

 containing the number of genera and species of restricted 

 as compared with wide areas. One example so taken deals 

 with the birds of various Californian areas. Here we find 

 in the restricted San Bernardino Mts. area (2000 sq. miles) 

 97 genera and 121 species, a ratio or index of modification 

 of 1*25 species to one genus ; in southern California (30,000 

 sq. miles) the figures are 153 and 199, giving an index of 

 ]"30; in the whole of California (158,000 sq. miles) the 

 figures are 186 and 347 and the index 1*87, thus showing 

 that as the area increases, " speciation ^' or specific modifi- 

 cation acts more strongly. 



Many other points are brought out in this essay in regard 

 to the theoretical explanation of these facts, and as to how 

 much speciation is due to isolation, the time-element and 

 other factors, but these cannot here be satisfactorily dealt 

 with and all we can now do is to draw attention to the 

 main thesis. 



Chandler on the Plumage of Circus hudsonius. 



•[Modifications and adaptations to function in the feathers of Cimts 

 hudsonius. By Asa C. Chandler. Univ. Cal. Publ. Zool., vol. xi. 

 1914, pp. 329-376, pis. xvi.-xx.] 



This paper gives a very complete account of the pterylo- 

 graphy, moults and plumage of the adult Marsh Hawk 



