v 
a 
cli 
of the operation is apparently to create a screen against the 
sand which the wind drives along. In the Algerian Sahara, 
where the winds come much more frequently from the east 
than from the west, the lark, according to Dr. Hartert, builds 
the wall on the east side of the nest. It would be most 
interesting to have observations on this point from the whole 
range of the various species which have this instinct, as 
probably in a district with west winds prevalent the wall 
would be on the west side. O0enanthe leucura occurs also in 
Spain, but there nothing is known of a building talent. If 
it should be true that the species has dropped the habit in 
that country, it would be a most instructive instance of the 
adaptability of the mind. Something of that kind we find 
in the Algerian Papilio machaon. As you know, the swallow- 
tail is a Palaearctic offshoot from an American stock and its 
larva feeds on Umbelliferae, as do the larvae of the nearest 
relatives in the Nearctic Region. In Western North America, 
however, there are two species (P. bairdi and P. indra) of 
which the food-plant is Artemisia, a composite. Now, in 
Algeria P. machaon usually feeds on Umbelliferae, but in very 
dry places or when the season is exceptionally dry, it takes 
to Retama, which can stand the drought. We found the 
caterpillars on this plant to the east of Khenchela, and 
Monsieur Le Cerf observed them on Retama near Alger in 
the dune district of Maison Carrée. Retama belongs’ to the 
Papilionaceae, a family rather remote from the Umbelliferae 
and Compositae. This instance of a new adaptation on the 
part of the swallow-tail seems to me worth recording. 
I append here a list of the more interesting Lepidoptera 
found on the High Plateaux grouped under four headings :— 
1. Lepidoptera exclusively found on the High Plateaux. 
Buchloé tagis pechi (Stdgr.), Satyrus briseis major Oberth., 
S. powelli Oberth., Melanargia syllius pelagia Oberth., Zygaena 
loyselis Oberth., Z. marcouna Oberth., Ichthyura pigra powelli 
(Oberth.), Nygmia phaeorrhoea xanthorrhoea (Oberth.), Lam- 
bessa staudingeri B.-Baker, Lemonia philopalus Donz., Holco- 
cerus powelli Oberth. 
2. Lepidoptera found on the High Plateaux and in the 
Tell, but not in the desert. 
Aa Ey, 
