The Insects of the "Danmark" Expedition. 51 



the other seeks rest on a blade of grass, the colour of which it 

 resembles so much. — The commonest day butterflies are however 

 the Argynnis, but like the following they are not met with on boggy 

 ground (nor in fact on the bare clay and stone plains). Yet w^e 

 may be surprised by these butterflies Hying up from ground where 

 the dry grass, Cassiope and other plants are only growing in hollows 

 here and there, until we observe that it is just these places which 

 afford the butterfly the most shelter. When this settles for example 

 on a stone or a Cassiope tuft, the reddish brown lichen covering the 

 former, like the purple-black leaf of the latter blends so perfectly in 

 colour with the butterfly that this cannot be seen before it starts up. 

 It is very shy, flying often far away before it again settles, and as 

 it "doubles" a great deal in its llight, it is more difficult to catch 

 than Colias. These butterflies are sometimes seen together, however; 

 in which case it is Argyimis that has come on to the grounds of 

 Colias and they playfully cross one another before proceeding on 

 their way. — More rarely and more singly we meet with the day- 

 butterfly Lycaena orbitulus on localities similar to those of Argynnis. 

 It is quite impossible to see this buttertly when sitting on the ground; 

 the gray under-side of the folded wings blends so perfectly with 

 the surrounding small stones. It does not fly far each time, but 

 irregularly and føirly quickly. — 



Among the night-butterflies the grayish Cidaria polata is by far 

 the most common ; it is also one of the first to appear and is met 

 with almost everywhere on the plain; it keeps mostly to the stony 

 patches, however, лvhere sitting on the ground or on a stone with 

 lichen-covering it is quite concealed by its colour-resemblance. — 

 More rare is the large Anarta Richardsonii, which keeps to similar 

 places and often sits on a large stone covered with gray lichens; if 

 we approach or if it notices one's shadow, it Hies high up in the 

 air and goes away in a long glide, carried by the wind, until it 

 settles on a new stone with a quick movement down to the ground. 

 Even if w^e have noticed where it has settled and steadily keep the 

 eye fixed on it, on creeping forward, we often fail to sec it, so per- 

 fectly does it seem to become part of the stone. As mentioned, it 

 is partial to the sun-dried gravelly spots with large stones and vege- 

 tation here and there, in contrast to the smaller Anarta Zetterstedtii 

 which is mainly met with along the grass-covered water-courses, 

 but is much more rare. Very common, lastly, is the small Penthina 

 groenlandicana, Avhich keeps mainly to the clumps of Cassiope found 

 in the hollows of the stony ground. If we approach these plants, 

 the small, white and black butterlly springs up and with characteristic 



4* 



