1914.] NATURAL SCIENCES OF PHILADELPHIA. 191 



12) represents the end' of the terminal hook as obliquely truncated^ 

 Eltringham (fig. 6) as a simple point. 



Figures 1, 2, and 3 on the left of the plate represent forms of 

 Limenitis from an area outside the limits of Scudder's monograph. 

 The claspers of L. lorquini (fig. 1) are seen to differ markedly from 

 those of all the other forms. Weidemeyeri (fig. 2), on the other 

 hand, closely resembles arthemis and ashjanax, although it is of a 

 stouter build. The main interest of the series of figures is, however, 

 concentrated in obsoleta (fig. 3). Just as the pattern of this species 

 was seen to be intermediate in many details between that of archippus^ 

 on the one hand and arthemis and weidemeyeri on the other, so is it 

 with the form of its claspers. To make sure that the appearance 

 represented in fig. 3 was not an individual peculiarity, Dr. Eltring- 

 ham made a second preparation, but with precisely the same results. 

 The comparison between figs. 2 and 3 suggests that the mimetic 

 form arose from an ancestral species with claspers more like those of 

 weidemeyeri than arthemis. Looking at these figures, some natural- 

 ists may be inclined to suppose that ohsoleta sprang from weidemeyeri 

 in the southwest, while archippus developed independently from 

 arthemis in the east and north. Such a conclusion seems to me 

 improbable. It is unlikely that independent lines of evolution 

 would have led to structures with the essential similarity that is to 

 be recognized between the forms shown in figs. 3 and 6 — I refer 

 especially to the hook below and the strong teeth above the end of 

 the organ — and still more improbable that such independent evolu- 

 tion would have led to the resemblances in minute detail that have 

 been shown to exist between the patterns of obsoleta and archippus. 



Remembering that these conclusions are founded on small differ- 

 ences between organs that are themselves very variable. Dr. Eltring- 

 ham has confirmed his results by making preparations from 3 indi- 

 viduals of archippus, 2 of obsoleta, 2 of weidemeyeri, and 2 of astyanax 

 arizonensis. He finds that the fine points or teeth are not only 

 variable in different individuals, but that they vary on the two sides 

 of the same individual. This he has shown by the careful drawings 

 reproduced on Plate V, where this want of symmetry is apparent 

 in nearly all the figures. The second specimen of weidemeyeri has 

 rather fewer teeth than the one figured. In a single specimen of 

 archippus floridensis (eros) the organs were somewhat larger than in 

 archippus and the clasper points were a little less acute. In spite of 

 great individual variability and the want of symmetry, the claspers 

 of the individuals shown in Plate V Exhibit recognizable characters 



