196 Genetical Studies in Moths 



and Cheimatobia has been derived ; the latter appears to have diverged 

 from their common ancestor at some fairly early stage in its existence. 

 With Venusia, owing to the period of its active life cycle, we are not at 

 present interested ; in the case of Cheimatobia matters are somewhat 

 different, for in opposition to the indications of its apterous and sub- 

 apterous females, it approaches so closely to Oporabia in all its other 

 essential characteristics as to render any investigation in that genus 

 incomplete without their joint genetical possibilities being considered. 



In view of this limitation in the number of species included one 

 would have anticipated that the genus would prove, from the standpoint 

 of specific differentiation, an easy subject for study; such has not, how- 

 ever, been the case, as only comparatively recently have the relationships 

 between the forms it includes been understood with any degree of exacti- 

 tude. As a result of recent researches it can now be confidently stated 

 that the genus comprises two species and two subspecies, the species 

 Oporabia autumnata with its subspecies 0. filigrammaria, and the species 

 0. dilutata with 0. christyi. So chaotic did the variation of the species 

 appear, and so prone were they to vary along parallel lines and to form 

 local races resembling each other, that entomologists, even whilst keeping 

 the subspecies 0. filigrammaria distinct, consigned the remainder of 

 the forms, comprising two species, one subspecies and countless local 

 races, into one specific dustbin which they labelled Oporabia dilutata. 

 Such a procedure would have been impossible had they had the slightest 

 knowledge of the insects not as dried specimens but as living creatures, 

 each with its special life history and specialised habitat. In this lumping 

 they were excelled by Meyrick\ who in this as in all similar cases cut 

 the knot of his difficulties by lumping all, the very striking 0. filigram- 

 maria included, under the same specific title. Ignoring the practice of 

 Mejo-ick as thoroughly unscientific, the action of entomologists in general 

 ended in the severing of two of the most closely allied forms, and the 

 uniting of two of the most physiologically diverse forms in the British 

 Fauna. This was most vividly proved by the almost perfect homology 

 of the chromosomes in the gametogenesis of hybrids between 0. autum- 

 nata and 0. filigrammaria and its absolute lack in the case of the dilutata 

 — autumnata hybrids. 



For the order which now obtains in the genus three workers are 



responsible, Prout, Allen and myself; Prout and Allen worked from the 



standpoint of the systematist and I from that of the geneticist, although 



necessarily my labours unearthed many facts of great value to systematics. 



^ Meyrick, British Lepidoptera, p. 224 (1896). 



