280 THE NATURALIST. 



SALiOACBiB. Salix retiisa, " Willd. 



Cyperacb^. Carex curvula^ All. ; C. ovalis. Good, ; C. nigra, AIL 

 Graminacb^. AgTOstis alpina, Willd. ; Aveiia sempervirens, Willd, (A. 

 striata, Lam.) ; Poa ceiiisiaj * AIL ; P. alj)ina, Willd. ; Festuca 

 eslda, Earn, j F. yiolacea. Gaud.; Aii^a siibspicata, (Trisetum 

 subspicatum, P. Beauv.) 



Of these seventy-two species grooving between the elevations of 2860 

 metres (9117 feet)/[snd 2877 metres (9172 feet), there are tliirty-five 

 which are also found in the Eanihorn ; and fifteen, printed in italics, at 

 the Jardin de la Mer de Glace de Chanionnix. I have counted tliirteen, 

 which are also found in all three localities, viz : — Stellaria cerastoldeSy Ceras- 

 tium latifolium, Sihhaldia procumbens, Erigaron unijiorus, E. aljnnus, 

 Omolotheca supina^ Poa alpina^ Phyteuma liemispliericum, Gentiana acaulis, 

 Linaria alpina, Plantago alpina, Carex curvula, Agrostis alpina. Of these 

 thirteen plants, the first seven are also found in the north, a new proof of 

 the common origin of tlie most vvidely spread alpine and Pyrenean species. 

 The six last are essentially alpine forms. Fourteen Lapland species, marked 

 with an asterisk, make part of the fiorula of the Pic du Midi ; this is at 

 the rate of twenty per cent, consequently less than for the Faulhorn and the 

 Jardin. But of these thirteen species, four grow also on the shores of Spitz- 

 hergon, viz : — Oxijria dlgi/na, Erigeron uniflorus, Silene acaulis, and 8axi- 

 fraga oppositifoUa, and thj?ee others, Poa cenisia, Braha nivalis^ and 

 Arenaria ciliata, are missing in Lapland, hut are found both on the Pic du 

 Midi in 43° Lat,, and above 2860 m.etres (9117 feet) and in SpitzbergeUj 

 under the 78° N. Lat., at the level of the sea. Eelatively to the the total 

 number of species, the flora of the Pic du Midi is richer ui arctic plants 

 than that of the Faulhorn or the J ardin, for their proportion is ten per cent, 

 against five per cent, for the alpine summit and the glacial island. Should 

 this difference be attributed to the greater elevation of the Pic, or to other 

 circumstances connected with the ordinary distribution of plants ? This 

 question can scarcely be answered in the present state of our knowledge ; but 

 this resemblance in the vegetation of three points so far removed from each 

 other, proves a community of origin, and consequently a common basis of 

 vegetation, which has been modified according to circumstances depending 

 on climate, geographical position, of a mixture of plants of neighbouring 

 countries, or even of species derived from those of the later geological floras, 

 of which we find the remains in the most recent formations. 

 * The species printed in italics in the FcHilhorn list, p.p. 172— -3, 



