THE SWISS SPECIES OF THE GENUS HESPERIA. 85 
The Swiss species of the Genus Hesperia. 
By B. C. 8. WARREN, F.E.S. 
(Continued from page 83.) 
AL. fritillum, Schiff. (cirsti, Rbr.) 
There are, among the Swiss Hesperias, but two species which are 
confined entirely to the plains, armoricanus and fritillum. Of these 
the former is double brooded, but fritillwm is not. In spite of this, it 
is seldom to be found on the wing before the first days of August, and 
in backward seasons it frequently does not appear before the middle 
of the month. I have never seen a specimen from the Valais, and 
have so far only taken it in its well known locality of Hclépens, where 
it is abundant all along the hill side above the marsh. All the grass 
on these slopes is burnt brown by the middle of August, it being only 
in certain hollows and places sheltered by the undergrowth and trees 
that any vegetation is left. These places are the most frequented by 
such butterflies as are still about, but frztillum is only a very occasional 
visitor to them. So much so is this the case that the first season I 
worked the locality for fritiilwn I only got three specimens and came 
to the conclusion that its headquarters must be elsewhere. The fact 
is, however, that fritil/wm prefers the more arid spots. Any place on 
the hillside where the vegetation is completely burnt up there one will 
surely find fritillwm, and though one seldom sees more than one or 
two specimens simultaneously, a half hour spent on one of these 
barren stretches will produce a fair number. Almost all the speci- 
mens thus captured will be gs, the @, most likely, hides among the 
long withered grass, and so is very difficult to find. 
Fritillwm is an easily recognised species; the heavy square white 
markings, and the broad and straight-edged intra-discoidal spot on the 
upperside of the forewings, the broad white band on the upperside of 
the hindwings, the deep coloration and prominent nervures of the 
underside, all combine to make the species unmistakeable. It is never 
likely to be mistaken for any other species, being, in my experience, 
one of the least variable species of the group. The amount of white 
on the upperside shows some tendency to vary, and the basal spots on 
the underside of the hindwing are lable to a certain amount of 
variation too; as one, not unfreqently, finds specimens in which they 
are somewhat rcduced in size. Such examples, if the rest of the white 
markings on the underside are also slightly reduced, have a certain 
resemblance to an aberration of malvae or malvoides, in which the 
white markings are enlarged. I do not think that a careful observer 
could be led into the error of identifying such an aberration as any- 
thing but fritillum; but the converse might quite possibly happen. 
This aberration will be mentioned again, in connection with matvotdes. 
The var. eatensa is but poorly represented by the specimens from 
Eiclépens, being both rare, and seldom, if at all, ofa pronounced formation. 
Still, as I am only acquainted with the species in one locality, it is 
quite possible that in others it may be less rare, and more developed. 
H. serratulae, Rbr. 
In Switzerland, serratulae develops two distinct forms, which have 
been called the plain and mountain races; though neither form is by 
any means confined to either the plains or the mountains. Still, the 
May, 1920. 
