( 466 ) 



the neighbourhood of the davats; but it is never seen on the vnst reddish buff 

 stony plain, where G. t. carol inae occurs. 



Ou the hills Euchloii charlonki was flying, and in a mostly dry river valley 

 some fifteen kilometres to the south we found a rich vegetation and Euchloii 

 charlonia dMAfalloai were common. How different a locality to find the latter, 

 to the neighbourhood of Biskra, where it only flies on the ragged, torn and dry 

 dark-coloured height of the Djebel bou Ghezal I The reason, however, was easily 

 understood, for its food-plant, Morecandia arcensis var., grew in abundance. 



Some pools of water were alive with millions of Apos numidicus, a crustacean 

 which is found in almost every pond and pool from Laghonat to Ghardaia, and 

 elsewhere. A vast j)laiu extends to the south of Laglionat, the ground reddish 

 buff, with innumerable stones of the same rufous buff colour, aud a scanty 

 vegetation of low thick bushes of a greenish grey colour, consisting of hardly 

 more than three species of plants — Artemisia herha-alha dominating over 

 everything else, and often for miles the only plant noticed. Anabasis urticidatu and 

 llaloxijlon artimlatum. 



In certain places sand appears, and there halfa grows, aud now aud then 

 a Ueliardhemum hirtam with pretty yellow flowers gladdens the eye. On the whole 

 this .4»fe;«/s/«-covered plain, with its innumerable stones and scanty bird life — 

 sometimes a Iloabara, Galerida tlieklae carolinae, the pretty Otocori/s bilopha, an 

 Aminomanes, or the rare thick-billed Rhamphocorys clot-bey is seen, but hardly 

 anything else — is the most fatiguing desert of all, while it lacks the serene beauty 

 of the sand-dunes. We were glad that we were able to pass through this 

 desolate country at motor-speed ; but this, unfortunately, was frerjuently rudely 

 checked ! The last night in Laghouat a very heavy thunderstorm with terrible 

 rain came down, and the " road " — if it cau be called by that name, for, thougli 

 generally good, in places the road was hardly visible — had greatly suffered. Soon 

 after Laghouat we got into deep mud, of which there had been no sign a couple 

 of days before, and afterwards we took the wrong road and became stuck live 

 times in deep sand. It necessitated much labour iu each case to get off agaiu : 

 bushes of Artemisia, bunches of Sfipa (if there were any) and whatever we could 

 get hold of, had to be torn out and placed iu front of the wheels, aud then, with 

 all hands on the wheels or body of the carriage and " full speed ahead " we began 

 to move, but often not before a considerable time had elapsed. We were, 

 therefore, quite glad when the first " dayats " were reached. What an extraordinary 

 sight — a park-like clunij), sometimes of great extent, of fine ohl trees in little 

 depressions in the middle of the most desolate stony desert ! These dayats with 

 their old Pistacia-trees (PI. XXV.), Betoum of the Arabs, Pistacia atlantica of 

 botanists, always stand in little depressions where the water remains in the rainy 

 season, and there is but little vegetation except the fine, thick, often gigantic 

 Betoums, an outer ring of prickly " sarib " or "jujubes," Zizyphus lotus, -Mid in 

 the surrounding desert the endless Artemisia, aud other low, greyish green plants. 



The soil is like the dry mud of a barn floor, without undergrowth, except 

 a few Zizyphus-bushes; aud only iu a few dayats the Arabs plant wheat in 

 favourable years, like the present one. The fears, expressed by I'rofessor 

 Massart iu 1898 (^Bull. Soc. r. de botan. dc BeUjique xxxvii p. :U4) that 

 J'istacia atlantica was doomed to extinction are absolutely groundless. When 

 Massart visited the dayats, there had been an exceptionally long j)eriod of rainless 

 years aud everything was parched and unusually dry. The author did not see 



