THE SWISS SPECIES OF THE GENUS HESPERIA. 119 
mountains ; flying up and down the edge of precipitous torrents, where 
its only Lepidopterous companions are a few small moths. One may 
walk for hours over a rhododendron-covered Alp, where cacaliae and 
numerous other species of Alpine butterflies abound, and if there is no 
water about, never see andromedae; but on coming to a little stream, 
or even a small pool, such as is frequently seen in districts where there 
are many cattle, a few moments search will almost certainly 
disclose it. I have experienced this many times, and have often gone 
considerable distances out of my way to verify the fact. It requires, 
however, a certain amount of practice to catch, or even mark with the 
eye, this lively species in such localities. 
Andromedae is a very distinctly marked species, and is not one 
which the collector is ever likely to find difficult to name; but, 
I believe the feature most usually trusted to for identifying the species 
is the presence of the three small white lines, nearest the base, on the 
inner margin of the forewing upperside. Now this character when 
taken in connection with the formation of the median band underside 
hindwing, gives a combination of markings characteristic of 
andromedae, but has this drawback, the three white lines are, not 
infrequently, wanting, or reduced to two or one. In such gases, 
anyone wholly dependent on these marks would probably record the 
species as cacaliae. The underside hindwing, however, offers a sure 
means of identification. The two light spots next the inner margin 
form a more or less perfectly shaped exclamation mark, on a dark 
eround. This is found in no other species (see notes on cacaliae) and 
with the characters of the group makes the species unmistakeable. 
Andromedae is not a very variable species, such variation as I have 
observed being principally the result of enlargement of the white 
markings of the underside. The only aberrations of the upperside I 
have seen are a tendency to a great increase of grey scaling, giving the 
species an almost silver appearance; and the aberration already 
mentioned in which the white lines on the inner margin of the 
forewing are wanting. The extreme form is rare, | have seen about a 
dozen, but transitional ones, with only one or two lines present, are of 
frequent occurrence. 
Of underside aberrational forms the commonest is that in which 
the two spots of the exclamation mark are joined, owing to the 
elongation of the basal one, they never, however, lose their character- 
istic shape; nor, therefore, their value as a distinguishing character. 
This aberration is found in both sexes. 
An apparently very rare form (in my Swiss series of about a 
hundred specimens there is only one, and I have never seen a second) 
is that in which the costal basal spot is practically joined to the costal 
spot of the median band. I have only noted a tendency to this form 
of variation in one other species, namely serratulae. In my specimen 
the spots do not absolutely meet, but they so nearly do so, that it is 
probable that very rarely one would find a specimen in which they do. 
In another rare aberration, we find the central spot of the median band 
joined to the costal basal one. The extreme form of this Is usually 
accompanied by the union of the two spots of the exclamation mark ; 
transitional forms, with the central spot of the band considerably 
extended towards the basal spots, are fairly common. 
The var. reducta is found in several degrees; the extreme aberra- 
