64 CLIMATIC CAUSES AFFECTING THE DISTRIBUTION 
recorded as having been once taken near Eastham, till last 
year (1882), when I saw it in great abundance near Malpas 
A. Selene, T. Quercus, and 7. Rubi, I have never seen in our 
district, though they have occurred in it, and I can find no 
record of the occurrence of Z, Alveolus in it. 
Of the 22 species which are confined to the more Southern 
parts of the Island, G. Rhamni occurs occasionally in our 
district. The range, however, of this insect does appear to be 
determined by its food plant, as neither species of Rhamnus is 
found (according to Watson) in Lancashire or Cheshire. One 
species is, however, found in Flintshire, but itisrare. C. Edusa 
is found abundantly in some years, ¢.g., in 1877 ; H. Tithonus is 
tolerably common; V. Polychloros is recorded by Mr. BrockHoLes 
(one specimen) and Mr. Greeninc; G. C.-a/bum is occasionally 
taken all over the district, but seems to be becoming scarcer ; 
A. Paphia is found in Flintshire and Denbighshire ; Z. 4gon is 
found at Bidston and Delamere; and P. Linea has been taken 
at Eastham. This makes 8 of the 22 Southern species which 
reach our district, 
Of the 3 Northern species we have only C. Davus, which is 
found at Delamere and near Minera; of the 7 local species, 
none; and of the 3 ‘ Stragglers” only V. An/seopa, which’ was 
taken in 1872 both by Mr. Brocknozzs at Neston, and by 
Mr. F. Leatuer at Delamere. 
In Chester 
Gt. Britain. District. 
Species generally distributed ..., 28 - 27 
Southerng Species). nite ieistenorst iat 22 8 
Northern Fane apiece, cue ea menthol 3 I 
Local  Gantimtner ose one 7 = 
Suncraulas Shao Bale Reman ae 3 I 
63 37 
Of the total number (63) of species occurring in Great Britain, 
37, or 58°7 7 have been found in our district. On the other 
hand, the *S. Eastern Counties of Kent, Surrey, Sussex, and, 
Hants, and again, the 8S. Midland Counties of Herts, Bucks, 
Oxford, Northampton, Huntingdon, Bedford, and Cambridge, 
have 57 species, or over 907; and the Eastern Counties 
of Essex, Suffolk, and Norfolk, have 56 species; while the 
S. Western Counties of Wilts, Dorset, Devon, Somerset, and 
Cornwall, though in part lying farthest 8., and with a much 
more genial winter climate, have only 52, and I have no doubt 
that the species found in Devon and Cornwall alone are con- 
siderably fewer. 
We find therefore that there is a falling off in the number of 
species as we go from E. to W., and still greater as we go N.W. 
rather than N., for Yorkshire has (excluding extinct species) 46 
against our 37. Now if we look on the Continent we shall 
* These groups are the divisions adopted in Symon’s British Rainfall. 
