1886. 259 



This form is even smaller with darker brown-black anterior wings, and shows 

 more and broader white markings than cajula. In the specimen of AlpheraJcii 

 before me, the posterior wings have only the three large spots before the hind mar- 

 gin, which are in it not confluent. Otherwise the markings of the anterior wings 

 are similar, the antennse are also dark, and the thorax also bears the two reddish lines. 



I am certainly of opinion that a larger number of specimens, 

 especially from different localities, would enable us to unite Arctia 

 cajula with AlpheraJcii. 



Blasewitz, Dresden : 



January Wth, 1886. 



ON THE mCONSTANCY OF A QENEKIC CHAEACTEE m 

 NEPHERONIA ARABIC A. 



BY ARTHUR G. BUTLER, F.L.S., F.Z.S., &c. 



In the separation of species of Lepidoptera into genera, it has 

 Ibeen long admitted that neuration is an item of primary importance, 

 and the presence or absence of a vein in either front or hind wings is 

 regarded as an amply sufficient character upon which to found a new 

 genus ; that this is so, as a general rule, I do not deny, but that it is 

 a rule with exceptions is evidenced by the abnormally-veined indi- 

 viduals of well-known species, to which, from time to time, I have 

 thought it of importance to call attention. 



I have long held the view that, as no species or genus is abso- 

 lutely fixed and stationary, it should be possible not only to find links 

 between species, but also between genera, and I have looked upon 

 aberrations of structure especially when often recurring in individuals 

 of the same species, either as the commencement of a new generic 

 type, or as a reversion to an ancestral type. 



In my revision of the sub-family Pierinw, in vol. i of " Cistula 

 Entomologica," I separated the genera into three main divisions, dif- 

 fering in the number of sub-costal branches in their front-wings — 

 whether three, four, or five ; and, so far, I had never had cause to 

 doubt the completeness of this arrangement ; but, wishing recently to 

 find some good structural character for separating N. JBuquetii and 

 allies from NepTieronia, to which externally they bear but little 

 resemblance, I carefully re-examined their structure, beginning with 

 our seven examples of N. arahica ; to my astonishment, the first 

 specimen I examined possessed only four instead of five sub-costal 

 branches ; I took up another, and yet another specimen, until I had 

 examined five, still with the same result ; when, iust as I was begin- 



