144 LEPIDOPTEKA. 



possibly have undergone a sea voyage. Stray specimens 

 continued to be noticed to the middle of September. One 

 was recorded in Scotland on September 20tli, and two 

 stragglers in Norfolk as late as October 5th and 7th. 



Mr. H. T. Stainton, writing upon the subject, expressed an 

 opinion that these specimens were introduced by a migratory 

 movement of the species, and he indicated Norway as the 

 probable point of departure. Living at Norwich at the time, 

 and having exceptional opportunities of obtaining information 

 on the subject, I was indisposed to accept this view, and 

 brought forward all the available evidence in favour of the 

 native origin of the specimens, but am now convinced that 

 migration was the sole cause of this sudden visitation ; and. 

 taking into consideration that the usual line of travel of many 

 birds to and from Norway is through Norfolk, am convinced 

 that Mr. Stain ton's suggestion was most reasonable and pro- 

 bable. An earlier record by Mr. Wailes, in his " Catalogue of 

 the Lepidoptera of Northumberland and Durham," to the effect 

 that Mr. William Backhouse had seen great numbers of this 

 species drowned in the sea on the Durham coast and in the 

 River Tees, about the year 1820, is strongly corroborative of 

 this view, since these drowned specimens could hardly have 

 come by their fate in this way if strong and fresh, but must 

 have been fatigued by a long flight, and then in all proba- 

 bility, constrained, by some sudden squall or change of wind 

 to colder, to drop hastily before they reached land. Stronglj' 

 desirous as every one must be of claiming this lovely species 

 as a permanent resident, all the evidence goes to show that, 

 in the enormous majority of cases, the specimens seen are 

 but migrants. To this the absence of records of the larva 

 most conclusively points. Yet it is strange that this should 

 be the case, since the insect is common in Norway, notwith- 

 standing its colder climate. 



There is a widely spread belief in this country that all 

 British specimens have the marginal band white, and that 

 this peculiarity indicates native descent ; but no dependence 



