VARIATION IN EUROPEAN LEPIDOPTERA. 



75 



ately for British naturalists, are found in Great Britain. We have 

 here again, a group of numerous species (comprising no less than 

 twenty-nine European forms), coloured uniformly and monotonously 

 with brown, reheved by a fulvous band of eye- spots; and some of 

 these species are, moreover, very inconstant, both in the number and 

 intensity of their markings. On examination we can trace characters 

 running through five or six species, more or less modified until they 

 disappear. Compare, for instance, the median band on the under side 

 of the hind wing of E. Ligea ; a wavy streak of white reaching from 

 the costa to the centre of the wdng, where it terminates in an angular 

 form, with the similar bands of E. Medea, E. Neoridas, and E. 

 Euryale : and note how E. Medea and E. Neoridas retain, in most 

 specimens, a costal whitish trace, while in E. Euryale the terminal 

 whitish angle only is retained, and this only in occasional specimens. 



Compare, too, a good series of CcEnoJiympJia Davus and its variety 

 Philoxenus (^Rothliebii) and intermediate aberrations, noting the 

 median band of the under surface of the hind wing and the eye- 

 markings sometimes completely absent, and sometimes most con- 

 spicuous ; compare such a series, I say, with one of C. Pauiphilus. 

 Here, too, we have a median band, in England generally reduced to 

 a central patch, and no eye-markings, but on the Continent some- 

 times having a continuous band across the wing, suffused, it is true, 

 but explanatory of the patternless trace left in the EngHsh form, 

 and bearing eyes often well and distinctly delineated. C. Arcanius, 

 too, is as variable as C. Davus in the band of the hind wdng, and is 

 linked with C. Satyi'ion by an intermediate forma Darwiniana, having 

 the upper side of one and the under side of the other. But I must 

 not weary you with examples. A remarkable phenomenon in, 

 shall I say, the history of species, is that occasionally all or most of 

 the insects of a wide district, though grouped under different genera, 

 are found to be stamped by some common peculiarity, such as that 

 notable configuration of wing found by Mr. Wallace to prevail among 

 the Pieridse and Papilionidae of the Isle of Celebes ; thirteen out of 

 fourteen of the latter, and ten of the former, having the costa of the 

 fore wing elbowed near the base, or the apex pointed and sometimes 

 hooked. Or, again, the striking prevalence of a white neuration of 

 the undersides of South Russian Rhopalocera : for instance, Erebia 

 Afer, Triphysa Phryne, Satyr us Ant he, S. Autono'e, S. Hippolyte, and 

 Epinephile Narica, belonging to four different genera. Such facts 

 seem to me strongly suggestive of similar peculiarities having had a 

 similar derivation. 



I will now take up my subject proper. . . 



Nov. 1884. 



