Insects* 



6279 



types together. The oldest I quote from Stephens' work, under 

 P. Artaxerxes, — "I once observed it on Dartmoor, 23rd August, 1823. 

 — Dr. Leach;'''' and Mr. Stainton, in his ' Manual,' under P. Agestis, 

 says " A singular variety, with a while spot on the upper side, in the 

 centre of the fore wings, was talien near Brighton, last July (1855), by 

 Mr. H. Cooke. The under side agreed entirely with the ordinary 

 appearance of P. Agestis. Mr. Bond, one of our best out-of-door 

 naturalists, and an excellent Lepidopterist, informs me that he has 

 occasionally seen a specimen in the South, with a small white spot on 

 the wing." Mr. Vaughan says he once took a specimen near Bristol, 

 with a clear white ring round the black dot in the anterior wing and 

 Mr. Sircom, in a communication to the 'Zoologist,' 1844 (Zool. 773), 

 mentioned other similar cases in the South. From Yorkshire, north- 

 wards, these white-spotted specimens are numerous, and ultimately, it 

 would seem, the only form we have. I think, therefore, we may 

 reasonably conclude that the presence of a white or of a black spot 

 will not suffice to establish the fact of there being two species. 



Finally^ we have to consider the point of ocellated or non-ocellated 

 spots on the under side ; in other words, whether the absence or 

 the presence of minute black dots in the centres of the white spots 

 underneath be sufficient to divide the specimens into two species. I 

 may premise that the presence of this black dot in the discoidal spot 

 of the under side of the anterior wings destroys the Fabrician and 

 Haworthian " puncto medio utrinque albo," as well as Stephens' 

 " utrinque macula discoidali alba," at once ; and yet the latter author 

 seems to have overlooked the fact that his variety ^, as given above, 

 necessarily had this effect ! The examination of all our British Poly- 

 ommati, with their varieties, and of the best figures of the European 

 species, convinces me that the only spots or ocelli that are never 

 wanting are those placed at the apex of the discoidal cell of each wing, 

 and consequently, that either the absence or the presence of any one 

 or more of the others, and, a fortiori, their having pupils or not, affords 

 no unvarying specific character. I might enlarge upon this point, but 

 refrain, and proceed rather to apply the proposition to the insect 

 before us. Mr. Gregson, of Liverpool, one of our most observant 

 Lepidopterists, is of opinion, founded on his long and wide-spread 

 experience in collecting, that the full development, and also the 

 brightness of the ocelli in these insects, depend much upon the warmth 

 of the season of their appearance in the perfect state. According to 

 this law, which certainly obtains amongst insects generally, when 

 undisturbed by local causes, we might expect, and in fact find, that. 



