158 fJ"'.r. 



■which he apparently does not consider o£ sufficient importance to 

 Avarrant the establishment of varietal names. 



A casual comparison of specimens from Calgary, Alberta, Avith 

 others of British origin reveals no very striking difference, beyond the 

 fact that the North American examples are, in general, duller in appear- 

 ance than the British, which have their dark and light markings much 

 more contrasted. 



An examination of the male genitalia of British and North American 

 specimens reveals at once marked differences. The general form of these 

 organs is quite obviously of the same type, but there are several points 

 of difference which are better shown by the Plate than by any descrip- 

 tion which I can give. I would, however, point out that the uncus 

 in the North American form is bifurcate, whilst, apparentl}^ in the 

 British form it is single.* Of this I am not thoroughly satisfied, but I 

 had at the time of making the mount only one available male, and the 

 appearance of the uncus, whilst being in shape quite distincth'- different 

 from that of the North American form, gives one the impression that it 

 might be bifurcate. The genitalia of the British specimen lacked a 

 portion of one harpe, but one side is sufficient to show the difference, as 

 in these forms the organs are sjanmetrical. 



With reference to the imago, it is apparent on a careful examina- 

 tion that the wing-markings differ considerably, and the two enlarged 

 photographs show the differences well. I am not at the present moment 

 sufficiently familiar with the technical terms for the wing-markings to 

 give comparative descriptions, and I would like to see these forms 

 investigated further b}^ a competent systematist. 



The questions to which a study of these relationships gives rise are 

 exceedingly interesting, especiall}^ the question of the values of certain 

 chai-acters in the determination of specific differences. Are the points of 

 difference of sufficient value to warrant the establishment of another 

 specific name, or are these two forms just races or varieties of one 

 species ? Of course it is useless to attempt to establish an3'thing on 

 the examination of a few specimens from two localities, of a species with 

 such a universal distribution, but I am convinced that an examination 

 of large series from the various parts of the world in which this moth 

 is found, particularly from Eastern North America, Eurojje, China, 

 and Japan, would give us valuable information on the part played in tlie 

 yariation of a species by its environment. 



* Described as tonfjue-sliartd by Mr. Tierce [Gcnit. Brit. Noct. p. 67, pi. 24 (iyn7)].— Eds. 



