MOUNTAIN FLORA OF GREAT ATLAS. 439 



Umbelliferce would be increased if the whole Flora were better 

 known. Subject to this remark, it wiU be seen, as might be ex- 

 pected, that the constituents of the Great Atlas Flora show more 

 analogy with those of the Sierra Nevada and Bulgardagh Floras 

 than with those of Dabnatia and the Southern Alps ; but the 

 proportion of Composifce is larger than in any of them (nearly 

 14 per cent). In comparing the vegetation of a small district 

 with that of a large one it must be recollected that a small 

 natural group containing a few widely spread species, such as 

 Geraniacece, is likely to show a larger percentage proportion to 

 the whole Flora in the small district than in the larger one. It 

 may happen that the same species are spread through both re- 

 gions ; but in one case the number is to be compared with a 

 small total, in the other with a much larger one. This remark 

 has a bearing on the fact that in the Great Atlas Flora the 

 natural orders that bear an unusually large proportion to the 

 total number of the Flora are Leguminosce, CaryophyUeoe, Ru- 

 biacece, Papaveracece, Geraniacece, and Convolvulacece. On the 

 other hand, there is a remarkable deficiency in the natural 

 orders that especially characterise the Flora of the Alps, and in 

 a less degree, the high mountains of Southern Europe. These 

 are Ranunculacece, Rosacece, Saxifragece, Primulaceoe, Junceoe, 

 and GyperaceoB ; not to speak of Genfianece, which are here 

 altogether absent. 



If, instead of regarding the Atlas Flora as a whole, we ex- 

 amine separately the figures given in the several columns for 

 the middle and superior zones respectively, we find very different 

 proportions for the chief natural orders, except for Compositce 

 and Leguminosce which are in both very numerous. In the 

 middle region of the Atlas these two orders represent very 

 nearly one-fourth of the phsenogamous Flora. After these 

 Graminece, Rubiacece, Papaveracece, Geraniacece, Cistinece, and 

 Convolvulacece are, in the middle region, unusually frequent, 

 while Crudferce, Roscccece, Boraginece, and Liliacece are remark- 

 ably deficient. In the superior zone, on the other hand, the 

 proportion of Compositce and LeguminoscB is less excessive, 

 making jointly a little over one-fifth of the whole Flora of the 

 upper region. The most marked characteristic here is the very 

 large proportion of Gruciferce, being less by one species only 

 than the number of Compositce. Taking into account the 



