170 PROBLEMS OF GENETICS 



sentatives of the northern type might be rare. I admit that this 

 is a somewhat strained interpretation of the facts, and as yet it 

 is not entitled to serious consideration. Nevertheless I am led 

 to form some such expectation partly from the great difficulty 

 in the way of any other, partly from the evidence of the small 

 mixed sample found at Preuilly and partly from the statements 

 given by Oberthiir. There are moreover other features in the 

 general distribution of the species which make it improbable 

 that the dependence on climate can after all be so close. Pub- 

 lished lists are unfortunately of little use in deciding which form 

 occurs at a particular place, because, since the name Meone has 

 ceased to be used for the southern form, there is no complete 

 unanimity among authors as to the application of the names 

 egeria and egerides, and unless more particulars are given, either 

 name may be used for either form. Besides this, difficulty arises 

 from the fact that the intermediate type is not generally dis- 

 tinguished at all, and English collectors finding it, may easily 

 record it as the southern type. From Staudinger's note on the 

 distribution, I gather that he, on the contrary, reckoned the 

 intermediate with the northern type, as do the Speyers also. 

 The late Mr. J. W. Tutt was careful to distinguish the three 

 forms and has left several useful records. Easy therefore as it 

 might seem to be to make out the distribution of such a familiar 

 insect in its various modifications, there are serious practical 

 difficulties, and until long series are brought together with this 

 special object in view many obscurities will remain. 



With only the series from England, the west of France, and 

 Spain before one it would be easy to regard the successive series 

 of tones as a fair measure of climate ; the brighter the colour, the 

 hotter might one expect the locality to be. Such rough corre- 

 spondence is often to be observed in butterflies and birds. It 

 becomes impossible to take these simple views in the light of 

 more complete knowledge. Beginning with France the fulvous 

 egeria occupies the lower valley of the Rhone, probably from well 

 above Lyon, though I have no exact information respecting the 

 country above Avignon. According to Speyer it also takes the 

 department of Lozere. The same authority says that Puy-de- 



