252 THE ENTOMOLOGIST. 
Cinerascens (qa) ; but I feel sure that someone else would inevit- 
ably have supplied the deficiency, as soon as detected, and my 
object in making this one addition to the catalogue, already too 
long, is to secure uniformity in so far as the naming of a colour 
form permits of it. 
The fact that Hdusa is not an indigenous species in the 
United Kingdom increases rather than depreciates interest in its 
variation. Incidentally, in the western palearctic region it is 
the most stable species of the Colias group, for whereas Mr. 
Sheldon’s observations* and captures in south-east Russia 
indicate a normal habit of hybridisation among the “ pale” 
Coliads—e.g. C. hyale x C. erate—there is as yet no recorded 
instance, I believe, certainly in Britain and France, of hybrid 
Edusa x Hyale, although the two species are often on the wing 
at the same time, haunt the same localities, and must be in 
frequent contact all over Europe. The problem of the “‘ white” 
females in Colias remains a problem. All that can be 
hazarded is that the original form of Colias female was a pale 
form, and that the vellow normal form, disclosing a tendency to 
maleness, has succeeded in dominating the original until it has 
ousted the ancestral pale form altogether, and itself become the 
normal. As I remarked at the beginning of this paper, there 
are localities left in which the proportion of pale to yellow 
female forms is still pronounced. But they are few and far 
between ; and as the white form appears to be extremely rare 
in the vernal emergencies—if occurring at all except acciden- 
tally—the evolutionary transition of colour form in the female 
may be considered established.+ 
I trust the compilation which I have made will at least prove 
useful for reference to students of variation, as well as to col- 
lectors anxious to identify and name such departures from the 
type as they may have encountered in the fields in those golden 
years—for Hdusa years are usually golden years for the lepidop- 
terist in every sense—when this adventurous and beautiful 
butterfly renews its, alas !, fruitless efforts to enrol itself in the 
little army of true British butterflies. 
In conclusion, I wish to express my gratitude and thanks to 
Dr. Roger Verity, of Florence, Dr. Ubaldo Rocci, of Genoa, and 
Mr. C. E. Morris, of Le Cannet, Alpes-Maritimes, for the great 
assistance they have given me throughout, especially in regard 
to the seasonal appearances and forms observed in Sicily, central 
and north Italy, and the French Riviera respectively. 
Harrow Weald; 
January 21st. 1921. 
* « An Expedition in Search of Russian Butterflies,” ‘Entomologist,’ vol. xlvii, 
pp. 270-271, etc., 1914. 
+ Mr. Morris reports two examples of the gen. vern. which he refers to ab. helice 
(in litt., October, 1921). , 
