372 Dr. T. A. Chapman: 



though they are, are nevertheless important, is a conclusion 

 that is much strengthened by the fact that those of Lijcxna 

 minimus differ from them so little, that one would expect 

 them to be declared identical by those who fail to dis- 

 criminate between argiadcs and coretas, yet minimus has 

 usually been regarded as belonging to quite a different 

 group of L)/(\v)i/i'. 



We discriminate species now, on wliat we call ]^hysio- 

 logical grounds, and not on morphological. What I take 

 this to mean is that the germ plasma of distinct species is 

 more or less immiscible, of forms of one species it is freely 

 miscible. We hold this view, though as a matter of fact, 

 we cannot apply it in one case in perhaps a thousand ; 

 what we do do, is to form an opinion about it (always 

 involving the personal equation) from all the fncts we can 

 ascertain, not merely morphology, but habits, distribution 

 and everything else available. 



In the case oi coretas, the somewhat doubtful presumption 

 that it is distinct from argiadcs, is by the evidence of the 

 appendages raised not to certainty, but a long way towards 

 it, since it makes nearly certain, that, though opportunities 

 must frequently occur, the germ plasma of the two forms 

 never mixes. The appendages, slight though the differences 

 are, are quite constant, and no intermediates occur. In 

 the ordinary wing-markings, a good deal of variation occurs 

 in both species, and perhaps no one feature is constant, 

 though I have not as yet been in any serious doubt as to 

 which species a doubtful example belonged to, and where 

 the appendages of a doubtful specimen were examined they 

 always agreed with the conclusion that had been arrived at. 



When we come to the American forms amyntuJa and 

 comyntas, my material is quite insufficient to say whether 

 there are one, two, or more species in North America. 

 But specimens from Calgary and California have identical 

 appendages which are intermediate between argiadcs and 

 coretas but much closer to coretas than to argiadcs. Are 

 we to call them one with coretas ? 



I incline to the somewhat paradoxical view, that these 

 American forms are co-specific with both our European 

 ones, although these are " good " species as against each 

 other. 



A Central American argiadcs is by its appendages again 

 a distinct species though there may be intermediates con- 

 necting this with amyntula. In the absence, however, of 



