MAY AT THE ITALIAN LAKES. 216 



ground close by. Ilcwans fnciformis was seen at Ajtif/a reptans on the 

 13th, and two or three common butterflies were seen. The impression 

 received was that many insects would have been met with had the 

 weather been favourable. Near Brunnen, cases of Kpichnopterix 

 pulla were frequent, these nearly all produced 5 s a little later, the two 

 or three <? s that emerged were very densely black. 



A search was also made for larvffi of Pamassiiis apollo, and was so 

 far successful that two were found, the object being to compare them 

 with those of P. delius, if these could be met with later. To complete 

 this item I may digress so far as to say that on June 8th an excursion 

 in search of P. delius was made from Faido, where we were at the 

 time. The train was taken to Goeschenen, carriage to Andermatt, and 

 a walk thence as far as Oberalpsee. The temperature was pleasant at 

 Faido, cool ai Goeschenen, cloudy at Andermatt, misty and cold on 

 Oberalpstrasse. Returning, the walk from Andermatt to Goeschenen 

 was in face of an icy wind with hail and rain. The ground by the 

 Oberalpstrasse, where P. delius is found, and where the larva must be 

 abundant enough, was still under thick snow, as was everything at the 

 Oberalpsee and about the hotel there. By a curious stroke of luck a 

 small patch of 8axifra<ja aizoides was noticed beside a little stream on 

 the sunny side of the road, and two larvae of P. delius were at once 

 seen on it. Not another scrap of S. aizoides free from snow, i.e., 

 absolutely none other than this little patch was seen, and so the search 

 otherwise was in vain. The material for the comparison of the two 

 larvfe was thus perhaps adequate or nearly so, but certainly not too 

 liberal. A comparison of the two larvfe is made a little difficult by 

 the P. apollo being now full-fed, whilst the P. delius are only about 

 half their size and have still to grow. Both are very dark dull black, 

 with shining black tubercles, the tubercles glistening so as to look 

 steely blue against the dull black skin, in some lights. In both 

 species, there is, just above the supraspiracular tubercles (iii) a row 

 of yellow spots, three to a segment, on the abdominal segments, two 

 smaller just above the tubercle, and a larger one behind these. The 

 form of these spots varies somewhat, but I can see no specific diffe- 

 rences in this item. On the thoracic segments 2 and 3 the same spots 

 occur. In one P. apollo these only, in the other a trace of a further 

 spot; in one P. delius this trace is much stronger, whilst in the other 

 the fourth spot is nearly equal to either of the two smaller ones. This 

 extra spot is on the first subsegment, in front of the two ordinary 

 small spots. This spot is, therefore, better developed in P. delius than 

 in P. apollo, so far as my material shows, but it affords no reliable 

 specific character. The hairs on the tubercles and on the general 

 surface (black, and about 1mm. long) are the same, both as to length 

 and distribution, in both species. The only really definite point of 

 distinction that I can detect, is the well-known and very obvious one, 

 that the yellow spots in P. apollo are a deep yellow, almost orange, 

 whilst in P. delius they are of a pale bright lemon-yellow. The two 

 species would thus seem to have a colour character in the larvse (the 

 yellow spots) and a colour character in the imago (that of the antennal 

 scales) as the only points of separation ; yet so far as we yet know 

 these are so constant as to be quite adequate to establish them. The 

 larval food-plant is also apparently an existent character, though the 

 Spanish P. apollo is said to eat a Saxifraya, as well as several species 



