1Q0 [January, 
Btripes and the lateral swellings is changeable ; that, further, a gradual 
transition can be put together in the images, from the true Artaxerxea 
to the Medon of the continent, then full certainty can only be obtained 
through breeding from the egg. 
The Helianthemtim, as food of the larva, no doubt produces L. 
Artaxerxes, the Erodiwn (in southern countries, besides cicutarium, 
certainly also other species), X. Medon. That the latter does not lay her 
eggs with us on Relianthemimi, 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 JDiurnce 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 larvse wiU 
all prefer to die of hunger rather than accept the Helianthemim ; 
which means that Artaxerxes will turn out to be a species difierent from 
Medon, however much their larvse may resemble each other in build, 
pubescence, and colouring. 
ON THE EUROPEAN SPECIES OP SYRPEUS ALLIED TO 8. BIBESII. 
BY G. H. VEBEALL. 
The " rihesii "-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 
first 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 bei-Qg 
