112 [October, 



though he did not believe tliem distinct. Had he sent a fair series as they were taken, 

 including these puzzling specimens among their congeners, I am tolerably certain Mr. 

 Barrett would have had no difScuIty in the matter. 



Can any one name with certainty an odd specimen of A. p.ii and tridenit, of C. 

 alsines or blanda, without comparison of others ? Yet with a fair series to examine 

 and compare, there is no great difEculty with either. No one supposes that because 

 of the difficulty of naming an isolated example of one of these insects that the 

 species are identical, though they may occur at the same time and place. How much 

 less reason then for fusing crepuscularia and hiundularia, when they actually occur 

 at dilferent periods of the year, and are known not to be two broods of the same 

 insect. The difficulty with the larvae is not greater than obtains with some of the 

 Zygmna, and the perfect insects of these are so puzzling that probably no two Lepi- 

 dopterists agree precisely as (o the number of species they recognise. Here (county 

 Durham), which I sui^pose Mr. Barrett would call a northern locality, we get 

 biundularia in May and June. They are always of the normal form, typical 

 hiundularia. I have more than once reared it from the egg, and never got any departure 

 from the type. Yet this is a district where dark varieties of many species occur not 

 uncommonly. Mr. Barrett concludes that it is " unreasonable to attempt to keep up 

 the purely artificial distinction between these two forms." To me it seems much more 

 unreasonable to attempt to ignore the truly natural distinction between them, merely 

 because in odd specimens we are. unable to find an artificial — perhaps I had better 

 say superficial — distinction. — John E. Kobson, Hartlepool: September 8tk, 1886. 



Description of the larva of Pterophorus tetradactylus. — Early in the season of 

 last year, Mr. Eustace R. Bankes, of Corfe Castle, found a larva on wild thyme, from 

 which he bred a specimen of Pterophorus tetradactylus ; so, knowing my want of 

 the species, he this year very kindly made a special search for it, the result being, 

 that on May 20th, I had the pleasure of receiving three specimens from him, together 

 with several healthy growing plants of the thyme on which to feed them. 



Length, when full grown, about half an inch, and of ordinary Pterophorus 

 shape, i. e., plump, stoutest in the middle, attenuated at the extremities, rounded 

 above, flatter beneath ; head small and glossy, considerably narrower than the second 

 segment ; a tuft of short hairs springs from each tubercle. Grround-colour bright 

 pea-green, when younger {i. e., previous to the last moult) having a yellowish tinge ; 

 head yellowish-green, the mandibles and a spot on each side of them brown; the 

 broad dorsal stripe is of a considerably darker shade of green than the ground- 

 colour, and is powdered on each side with greyish-white ; sub-dorsal stripes of the 

 same dark green colour, but not so conspicuous ; spiracular stripes rather broad, 

 yellowish-grey ; segmental divisions and hairs white. When younger the segmental 

 divisions are yellowish-grey, and the hairs grey. Ventral surface, legs and prolegs 

 uniformly of the bright pea-green of the dorsal area. 



I bred no imagos, as the larvpe came to grief during my absence in London ; 

 but in tins case it did not much matter, for Mr. Bankes having fortunately reared 

 the imago from a similar larva the previous year, had thus made sure of the species. 

 Apart from that they were too large for P. parvidactylus, the other thyme feeding 

 species, which, moreover, Mr. Bankes believes does not occur in the district. — Geo. 

 T. PORRITT, Huddersfield : Septemher 3rd, 1886. 



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