62 SCIENCE PROGRESS. 



known as P. oregonia is a species much resembling machaon 

 in oeneral coloration. It is found in Washington Territory 

 and British Columbia. Another "species," P. bairdii, has 

 the upper surface largely covered with black scales, especi- 

 ally in the female, and in general appearance may be said 

 to resemble the asterias group more than the machaon 

 group. It occurs in Arizona without intermixture with 

 oregonia, just as the latter occurs in the north without 

 intermixture with bairdii. However at Glenwood Springs 

 in Colorado oregonia and bairdii were found flying together 

 by Edwards. 



By rearing eggs laid by the Glenwood females, he found 

 that both forms could be reared from females of either form, 

 eggs from bairdii females producing both bairdii and ore- 

 gonia, and eggs from oregonia producing both oregonia and 

 bairdii (statistics given). The experiments showed that this 

 is not merely a case of seasonal change, both forms occurring 

 in each brood. 



For our present purpose it is important to notice the 

 fact to which Edwards calls attention that the oregonia and 

 bairdii in the locality of intergradation were not for the 

 most part the pure forms as they occur in areas where there 

 is no intermixture. Some of the bairdii were typical, but 

 most departed in different degrees from the type, no two 

 being quite alike. The oregonia also departed from the 

 type in the direction of bairdii. Nevertheless as the whole 

 account shows, here there were two well-marked forms like 

 those elsewhere known as local species or races, breeding 

 together in one locality but not regressing to the mean form. 



I will now refer briefly to two examples of marked local 

 races, whose relations I have been myself endeavouring to 

 investigate. The cases are those of Pieris napi (the Green- 

 veined White Butterfly) and its Alpine var. bryonies, and 

 Pararge egeria (the Speckled Wood Butterfly) and its 

 northern form cgeriades. I have been collecting and 

 crossing these species for the past three seasons, and am 

 still far from arriving at definite results, but I mention 

 the subject here in the hope that others may be induced 

 to look out for some of the points to be observed. 



