353 



fng, that he might figure them for a work upon which he has long 

 been engaged, and to which this society has become a subscriber. 

 A few days after, I received the said chrysalids from Mr Logan, 

 and he at the same time mentioned that, acting on the information 

 I had given him, he had pursued the search for the chrysalids, and 

 had found them in considerable numbers. Those I had in my own pos- 

 session emerged from the chrysalis, either that day or the following ; 

 and since that time it has, of course, become easy to note the habits 

 of P. ArtaxerxeSy and a beautiful delineation of it in all its stages 

 of development will appear in Mr Logan's book, whenever its appear- 

 ance shall realize the expectations of his numerous subscribers. 



To go further into the description of its transformations at this 

 point would be to trespass on the subsequent but as yet unpublished 

 observations of Mr Logan, and I shall therefore leave it now, to say a 

 iQW words in conclusion on Polyommatus Agestis and P. Salmacis, 

 two insects so nearly allied to the one before us that they have been 

 at different times considered to be one species. On looking at the 

 drawings of these three closely allied insects, for which very faithful 

 and beautiful illustrations I am indebted to my friend Mr Dallas, we 

 perceive that P. Artaxerxes is readily enough distinguished by 

 the conspicuous white spot in the angle of the upper wing, while 

 P. Agestis has a black one in nearly the same position. These mark- 

 ings, though affording in themselves but slight grounds for specific 

 distinction, are nevertheless permanent in their character, and even 

 before we were acquainted with the caterpillars of the respective 

 insects, gave great probability to the opinion that the two were dis- 

 tinct, especially when taken in conjunction with the fact that P. 

 Artaxerxes is confined to Scotland and the north of England, and 

 P. Agestis as exclusively to the southern counties of England. Still 

 this was matter of opinion, and it is only now that M'e are enabled 

 by our own observations in Scotland upon P. Artaxerxes, and almost 

 at the same time by similar observations by Mr Harding and Mr 

 Stainton in London upon P. Agestis, to determine, as I think, finally 

 upon the specific difference of the two insects. The gentlemen I 

 have just named have bred P. Agestis from the caterpillar, and find 

 that it feeds upon Erodium cicutarium, a plant in natural affinity 

 and every other respect widely removed from H elianthemum vulgare. 

 When, therefore, to the slight but permanent differences of its exter- 

 nal markings and habitat is added the fact that the caterpillar of the 



