422 Mr. H. Jenner Fust on the 



sift the false from tlie true much difficulty has been felt ; 

 it has been thought better to err on the side of strictness, 

 and the mark of doubt " o " has been used perhaps too 

 freely, but it is so much easier to prove the presence of 

 a species in any district than its absence, that it is hoped 

 this mil be considered a fault on the right side. 



Another difficulty has been the absence of records of 

 the occurrence of the commonest species ; for whereas 

 the capture of such insects as Golias Eclusa, or Acherontia 

 Atropos, which, though constantly found, are considered 

 sufficiently rare to be always worth mentioning, have 

 been recorded over and over again, the records of such 

 species as Pieris hrassicce, rapce, and napi would have 

 been few and far between, had it not been for the infor- 

 mation afforded by my correspondents. 



The influence of the distribution of the food-plant upon 

 that of the species whose larvge feed upon it, the attach- 

 ment of some species to certain geological formations, 

 of others to mountains, and the different altitudes to 

 which they attain, are questions of deejD interest, and 

 worthy of the closest attention ; and should this paper 

 be considered worthy of being accepted as a starting 

 point, and local Entomologists do their utmost to add to, 

 and correct the statements therein contained, our know- 

 ledge of the distribution of species in Britain would make 

 rapid strides, and records of captures would gain a new 

 interest, and be much more valuable than now, when it 

 is almost impossible to know what are new facts in local 

 entomology, and what are mere repetitions. 



I have availed myself of the interval between the read- 

 ing and the publication of this paper to make the Tables 

 as complete as possible do^vn to the end of 1867. 



