196 MB. A. a. BUTLER ON THE MOTHS 



learning the names of tlie veins, numbers are given to tliem. It 

 is popular because easy to learn ; but is subject under unfavour- 

 able conditions to total failure ; for, althougb most Lepidopterists 

 have now adopted my method of using benzine in the exami- 

 nation of wing- veins*, cases may occur where by overlooking 

 the forking of a vein the identity of every other vein in the wing 

 is altered. 



The number-system is essentially a retrograde movement. I 

 need only refer to A^on Heinemann's ' Schmetterlinge Deutsch- 

 lands,' p. 6, where the veins are positively numbered from the 

 back forwards, from th e inner to the front margin. If the authors 

 of the system in question are consistent they are utterly opposed 

 to me in every thing ; what I call the front legs are their hind 

 legs, and the club of the antenna, where it exists, must be the 

 last thing to describe. When I first began to describe genera, 

 and found that Doubleday had numbered the three branches of 

 the median vein backwards, I though-t the error sufficiently 

 grave, and I carefully avoided repeating itf; but by what 

 argument the costal margin of a wing can be regarded as 

 posterior and the inner margin anterior (excepting with certain 

 Moths in repose upon a perpendicular surface) I must confess 

 myself utterly unable to understand. In speaking of a branched 

 vein like the median, it is in accordance with common sense to 

 call the first branch emitted the first and not the third ; there- 

 fore in this vein the branches have to be counted upwards ; but 

 this is no excuse for counting the last emitted branch of the 

 subcostal vein as first. I hold, then, that the number-system, 

 although easy to learn, is unreasonable and (excepting when 

 employed by very careful observers) worse than useless. 



Synoptical Diagnoses of the G^ewera q/ Urapterygidae. 



A. Primaries triangular, the outer margin not angulated. 



1. Secondaries caudate, or angulated at the extremity of the third 



median branch; subcostal vein of primaries 4-branched; first 



branch emitted before the end of the cell and united to the 



costal vein beyond the end. 



a. Subcostal branches of secondaries emitted almost from the 



same point; second and third median branches from the 



same point Urapteryx. 



h. Subcostal branches emitted from a footstalk ; second and third 

 median branches from nearly the same point. Tristrophis. 



* See Trans. Ent. Soc. 1870, p. 486. 



t I since find that my example has been followed bj other Lepidopterists. 



