Crossing relatively small portions of the plain, in place of always following the bends of the Oued M’Zab, about noon of the second day we reached the bordj Zolfana, in the valley of the Oued amidst low and narrow dunes, which are moving slowly across the flats. (Fig. 44.) No vegetation appears on the dunes, but on the fixed sand between them, or on the stationary dunes at the border of the flats, some plants are to be found. Among these the most abundant, but really not numerous, are _Euphorbia guyoniana_ and retam (_Retama retam_), which was often seen later along the line of march as well as in the vicinity of Biskra. Retam superficially resembles _Ephedra alata_ in having rudimentary leaves and green, reed-like branches; it is carefully avoided by animals, although _Genista saharæ_, a very similar plant, which grows in like situations between Ghardaia and Ouargla, is said by Massart (_loc. cit._) to be eaten greedily by them. (Fig. 43.) A short distance beyond the bordj the bottoms suddenly widened, the dunes disappeared, and for the remainder of the day’s march we passed through the richest vegetation we had seen since reaching the M’Zab region. (Figs. 45, 46, and 47.) Here the shrubs were of fair size and of sufficient abundance to give character to the landscape. About the 63 kilometers camp the leading species are _Retama retam_, _Ephedra alata_, and _Haloxylon schmidtianum_. On the hamada adjoining the flat are several species, including _Aristida ciliata_, _Artemisia herba-alba_, _Farsetia ægyptiaca_, _Farsetia linearis_, _Gymnocarpon fruticosum_, _Helianthemum eremophilum_, _Henophyton deserti_, _Marrubium deserti_, _Salsola vermiculata_, _Teucrium polium_, _Thymelæa microphylla_, and _Zollikoferia mucronata_. On the hamada just adjoining the place of our camp, however, there appeared to be _Haloxylon schmidtianum_, to the exclusion of other species.