116 



THE AMERICAN NATURALIST [Vol. XLIII 



Some years ago, in an address before the Entomological Society 

 of London, Professor Poulton raised the question whether the 

 ability to mate successfully was not after all something main- 

 tained by rigid natural selection ; and if I remember his argu- 

 ment correctly (I do not possess a copy of his paper), he 

 believed that differences in the sexual organs might be expected 

 to arise whenever selection ceased to operate. Since that time 

 Tower has produced striking evidence of the small amount of 

 divergence which suffices to throw an organism (in his instances 

 beetles) out of the race. In this connection it may also be 

 remarked that the singular fertility between different races of 

 men, dogs, cattle, etc. —many of these differing exceedingly in 

 many characters of color and form— may be attributed to the 

 effects of natural selection. The purest breeds of dogs, and no 

 doubt the best established races of men, are after all great 

 mongrels; and in the course of time no doubt interracial in- 

 fertility would be absolutely discriminated against. However 

 active the illumination may be in picturing causes and effects, 

 it can but pause before such cases of genitalic modification as 

 aiv desenbed by Dr. .1. B. Smith in his revision of the moths of 

 the L't'ims Ilomoptera and its immediate allies, just published 

 by the U. S. National Museum. In some of these moths the 

 sexual or-rans are extremely asymmetrical. "In the males the 

 asymmetry is between the harpes of the two sides, which in 

 extreme cases are totally dissimilar, with processes on one side 

 for which there is no counterpart on the other, and which are 

 rare \ entirely alike. The sheath of the penis or intromittent 

 ls a U;1 . vs ui<>re or less curved or bent, or even hooked, 

 in thefem™^ t0 ^ differences found 



The Lysorophidae. 



I). A. COCKERELL. 



OLOGY 



