ANNOTATIONS AND ADDITIONS. . 173 



geographical latitude. I would recall the limits, in respect 

 to elevation, of the birch and the common fir in a part of 

 the Swiss Alps, on the Grimsel. The fir (Pinus sylvestris) 

 extends to 5940, and the birch (Betulaalba) to 6480 French 

 (6330 and 6906 English) feet ; above the birches there is 

 a higher line of Pinus cembra, whose upper limit is 6890 

 (7343 English) feet. Here, therefore, we have the birch 

 intervening between two zones of Coniferse. According to 

 the excellent observations of Leopold Yon Buch, and the 

 recent ones of Martins, who also visited Spitsbergen, the 

 following geographical limits were found in Lapland : 

 Pinus sylvestris extends to 70; Betula alba to 70 40'; 

 and Betula nana quite up to 71; Pinus ceinbra is altogether 

 wanting in Lapland. (Compare linger iiber den Einfluss 

 des Bodens auf die Vertheilung der Gewachse, S. 200 ; 

 Lindblom, Adii ot. in geographicam plantarum intra Sueciam 

 distributionem, p. 89 ; Martins, in the Annales des Sciences 

 naturelles, T. xviii. 1842, p. 195). 



If the length and arrangement of the needle-shaped 

 leaves go far to determine the physiognomic character of 

 Coniferse, this character is still more influenced by the 

 specific differences in the breadth of the needles, and the 

 degree of development of the parenchyma of the appendi- 

 cular organs. Several species of Ephedra may be called 

 almost leafless; but in Taxus, Araucaria, Dammara (Aga- 

 this), and the Salisburia adiantifolia of Smith (Gingko 

 biloba, Linn.), the surfaces of the leaves become gradually 

 broader. I have here placed the genera in morphological 

 succession. The specific nama first chosen by botanists 



