18 ORIGINAL ARTICLES. 



of tlie Taurus ; and that tlie?e also descended proportionally lower 

 and spread much further to the eastward. Again, in the Sikkim and 

 Nepal Himalaya, I have found abundant evidence of glaciers having 

 descended to fully 4000 feet below their present level ; and this has 

 been corroborated by numerous observers in the western parts of the 

 same range ; so that there, too, the Cedar forests may be supposed 

 to have once descended several thousand feet, and to have extended 

 westwards along the Persian mountains, till they united with the 

 Taurus forests. 



It is more difficult at first sight to connect the Algerian vnth the 

 Asiatic forests ; but here the recent discoveries of extensive modern 

 changes in the form and extent of the Mediterranean basin come in 

 aid. It is not now doubted that the remains of the African Hippo- 

 potamus and Rhinoceros in Sicily prove a former continental extension 

 from the Tunis coast to that island, and the soundings between Cape 

 Bon and Sicily appear to corroborate this \\ew. It would be foUy 

 to assume it as certain, that the extension of these most recent disco- 

 veries will clear up the early history of the diffusion of the Cedars ; but 

 it is conceivable ; and if proved, it is reasonable to suppose that their 

 subsequent segregation in the four areas they now inhabit, was 

 effected by the warmth of the period which succeeded the glacial epoch. 

 During such a warm period the vegetation of the low levels would 

 be driven to seek colder localities, and to migrate both northward 

 and up the mountains, where it has left traces in the grove on 

 Lebanon, and in a few arctic plants which I obtained on the very 

 isolated summit of that mountain. Lastly, it is an established fact, 

 that aU plants of wide diffusion vary much, and that the extreme 

 forms occiu" towards the limits of the area they occupy ; whence, in 

 the case of the Cedars, what may once have been three prevalent 

 varieties in different parts of a continuous forest, became, by isola- 

 tion and extinction of intermediate forms in intermediate localities, 

 three permanently distinct races or sub-species, which we now recog- 

 nize as Lebanon, Algerian, and Deodar Cedars. 



EXPLANATION OF THE PLATES. 



Plate 1. — Cones and leaves of C. Libani, from the Lebanon. Figs. 1—4, Scales 

 of vaiious fonns from one cone, ripened at Kew; 5, Seeds fi'om the same; 6 — 7, 

 Anthers (magnified) ; 8, longest, shortest, and mean sizes of leaves, from native 

 specimens. 



Plate 2. — Cones and leaves of C. Atlatifica, from native specimens. Figs. 1 — 4, 

 Scales; and 5, 5, Seeds from the same; 6, Anthers (magnified); 7, longest, 

 shortest, and mean sizes of leaves, from native specimens; 8, Leaf, from yomig 

 cultivated specimen at Kew. 



Plate 3. — Cones and leaves of C. Beodara, from native specimens. Figs. 1 — 3, 

 Scales ; 4 — 5, Seeds ; 6, Anthers (magnified) ; 7, longest, shortest, and mean sizes 

 of leaves. 



