CHAP, XVI.] 



THE BKITISH ISLES. 



327 



preservation of some of the numerous species which are or have 

 been dependent on it. 



Mr. McLachlan has kindly furnished me with some valuable 

 information on certain species of Trichoptera or Caddis flies 

 which seem to be peculiar to our islands; and this completes 

 the list of orders which have been studied with sufficient care to 

 afford materials for such a comparison. We will now give the 

 list of peculiar British Insects, beginning with the Lepidoptera, 

 and adding such notes as have been kindly supplied by the 

 gentlemen already referred to. 



List of the Species or Varieties of Lepidoptera tvhich, so far as at lyresent 

 known, are confined to the British Islands. {The figures show the dates 

 when the species was first described.) 



DiURNI. 



1. PoLYOMMATUS DisPAR. " The large copper." This fine insect, once 



common in the fens, but now extinct owing to extensive drainage, is 

 generally admitted to be peculiar to our island, at all events as a variety 

 or local fomi. Its continental ally differs constantly in being smaller 

 and in having smaller spots ; but the difference, though constant, is so 

 slight that it is now classed as a variety under the name of rutilus. 

 Our insect may therefore be stated to be a well-marked local form of a 

 continental species. 



2. Lyc£ena astrarche, var. artaxerxes. This very distinct form is con- 



fined to Scotland and the north of England. The species of which 

 it is considered a variety (more generally known to English entomo- 

 logists as P. agestis) is found in the southern half of England, and 

 almost everywhere on the continent. 



BOMBYCES. 



3. LiTHOsiA SERicEA. North of England (1861). 



4. Hepialus humuli, var. hethlandica. Shetland Islands (186S). A 



remarkable form, in which the male is usually yellow and buff instead 

 of pure white, as in the common form, but exceedingly variable in 

 tint and markings. 



5. Epichnopteryx reticella. Sheerness, Gravesend, and other localities 



along the Thames (1847). 



6. E. pulla, var. radiella. Near London, rare (1830 V) ; the species in 



Central and Southern Europe. (Doubtfully peculiar in Mr. Stainton's 

 opinion.) 



NOCTU^. 



7. Acronycta myric^. Scotland only (1852). A distinct species. 



8. Agrotis subrosea. Cambridgeshire and Huntingdonshire fens, perhaps 



extinct (1835). The var. snhcceridea is found in Finland and Livonia. 



