190 



[January, 



stripes and the lateral swellings is changeable ; that, further, a gradual 

 transition can be put together in the images, from the true Artaxerxes 

 to the Medon of the continent, then full certainty can only be obtained 

 through breeding from the egg. 



Tlie Helianthemum, as food of the larva, no doubt produces L. 

 Artaxerxes, the Erodium (in southern countries, besides cicutarium, 

 certainly also other species), L. Medon. That the latter does not lay her 

 eggs with us on Relianthemum, I may assert as certain ; and there is 

 every probability that Artaxerxes does not select Erodium. 



But we have a right to expect that, if the young larvae, from the 

 egg forward, accommodate themselves to one or another food unusual 

 to them, their butterflies will also take the distinctions (or, to allow its 

 right to the influence of the climate, at least some of them) of the 

 species living upon that food-plant, thus establishing the proof of being 

 the same. Whether Artaxerxes appears in a second brood, as it 

 ought to do if it form the same species with Medon, I do not find 

 indicated. As hybernation (according to my observations on Medon) 

 is not at all easy, it will be best to choose the summer brood for 

 this experiment. The females of the Diurncs like best to lay their 

 eggs in the hours of the forenoon. Where this has been observed, 

 nothing is wanted but to cut carefully a few days later all the plants 

 near the spots, and to shake them over a white cloth, so as to secure 

 the number of larvse wanted. 



If the result answer my expectations, the Medon larva? will 

 all prefer to die of hunger rather than accept the Helianthemum ; 

 which means that Artaxerxes will turn out to be a species difterent from 

 Medon, however much their larvfe may resemble each other in build, 

 pubescence, and colouring. 



ON THE EUROPEAN SPECIES OP SYRPHUS ALLIED TO S. EIBESIT. 

 BY G. H. VEEEALL. 



The " riimi "-group of the genus Syrphus contains several species, 

 which, though closely allied, aff'ord nearly always, when carefully ex- 

 amined, good tangible points of distinction. By this group I mean 

 those species which have the eyes bare, and the abdomen elliptical (that 

 is, broadest in the middle) with at least three bands, of which only the 

 firbt is in either sex separated into distinct spots. The male of S' 

 corollce approaches this group, as the spots on the abdomen of that are 

 frequently strung together, but in the female they are always decidedly 

 separate. The group is most widely distributed, rihesii itself being 



