48 THE ENTOMOLOGIST’S RECORD. 
ever, do these local forms entirely replace the type. In Switzerland 
many localities produce some specialised form, which occurs - with 
more typical examples in about equal numbers, such a form being, as a 
rule, difficult to describe on paper in a manner useful to anyone 
unacquainted with it, but which looks very different when placed with 
specimens from other localities. The two chief races in Switzerland 
are, to a certain extent, divided by altitude; the one typical in Alpine 
and sub-Alpine regions, the other in the plains; each being subject to 
considerable variation, and frequently. appearing in the converse 
localities in small numbers. The typical mountain alveus are darker, 
with the white spots on the upperside of the forewing, small in size, 
and the ground colour of the underside of the hindwing of a 
yellowish tone, while in the plain form the white spots are much 
larger, and the ground colour of the underside of the hindwing is 
usually of a darker shade, and sometimes greenish. In this last 
particular, however, the plain form is exceedingly variable. _Alveus is 
well distributed throughout Switzerland, being more frequently met 
with in the mountains, where it is one of the commonest (though not 
the most widely distributed) species of the genus. In the plains, 
although occurring less universally, it is by no means rare. I have so 
far come across it in five lowland localities, namely, Follaterre, 
Vernayaz and Aigle, in the Rhone Valley, a little above Clarens, and 
Kclépens, and seen a few specimens from the lake of Thoune. The 
specimens from Kelépens, and some from Vernayaz, are worthy of 
special notice. While very obviously belonging to the plain 
form, they are remarkably similar to the mountain race of alveus 
from the Pyrenees. This southern Alpine race makes an extraordinary 
contrast with alveus of the Swiss Alps, and some years ago when first 
reading Prof. Reverdin’s description of foulguiert, I was struck with 
the resemblance between that (then) newly-described species and the 
Pyrenean alveus. The likeness was so great that I sent some specimens 
to Prof. Reverdin, who subsequently informed me that it was not the 
first time his attention’ had been called to this race of alveus, M. 
Oberthiir having suggested it was foulquieri, or a distinct species. The 
genitalia, however, do not differ from alreus. The Swiss form is 
racial in the Jura, but, as already noted, it occurs as an aberration at 
Vernayaz, and I also have a couple of specimens from the Grisons. 
Alveus is single-brooded, and is to be found on the wing by July, 
appearing just as early (sometimes earlier) at moderate altitudes as in 
the plains, though, of course, at great altitudes it is later, but 
never very much. ‘The existing records of the time of flight of alveus 
in the plains are almost useless, as it is impossible to tell whether they 
are referable to alveus or to armoricanus, and since the separation of 
this latter species, many collectors apparently hold the quite erroneous 
idea that alveus is entirely a mountain species. Of course, as a 
general rule, it will be perfectly safe to assume that the specimens 
recorded as taken in May and early June are armoricanus, particularly 
if any number have been taken, there can be no doubt on the subject ; 
but, while the facts just mentioned are undoubtedly correct, and alveus 
_is beyond question a single-brooded species, on very rare occasions a 
few prematurely emerged specimens have been taken in the spring, 
always, so far, isolated examples. I had the good fortune to take such 
a specimen once, on May 24th, at Branson, in the Rhone Valley. It 
