Xlviii PEOCEEDINGS OF THE 



these remnants, coupled with the apparently slow multiplication of 

 species, as the result of a continuous subsistence of the land from 

 the earliest periods, with few or none of those great convulsions or 

 gradual depressions and upheavals which have successively changed 

 the configuration and climate of those Eastern regions with which 

 Africa appears once to have been connected, and exposing them to 

 successive destructions or modifications of their old vegetation and 

 invasions of new races ? 



To Grisebach's notes on the connexions of the Tropical- African 

 flora with that of other countries I should have but few observations 

 to add. The intergrafting with the South- African flora along the 

 eastern side of the continent may well be attributed to climate and 

 other present physical conditions. The European character of the 

 higher mountain vegetation of Abyssinia and the Cameroons may be 

 indicative of the remains of that western flora, the mysteries of 

 whose distribution north and south of the tropics I have on several 

 occasions alluded to. The supposed evidences derived from the 

 vegetable kingdom of a once existing connexion between West Tro- 

 pical Africa and East Tropical America through an ancient Atlantis 

 gradually disappear on further investigation, No traces of a Western- 

 Atlantic or American vegetation were met with by Mann in the 

 mountains of Fernando Po and the Cameroons, nor by Dr. Hooker in 

 the Western Atlas of Morocco. The Tropical- American races found 

 in Western Africa are chiefly confined to the coast region ; they are 

 more generally identical than representative species ; and they may 

 have been brought over in the course of ages by some of those 

 means of transport which even now may occasionally occur, such as 

 the Gulf-stream, as mentioned by Grisebach. You may recollect, for 

 instance, a short notice by Dr. Dickie inserted in our Journal (Botany, 

 vol. xi. p. 456) of a green floating mass, twelve to fourteen miles broad, 

 crossed by Capt. Mitchell in the Atlantic, within 300 miles of the 

 mouth of the Gambia, which had evidently, in Dr. Dickie's mind, come 

 from some part of America within the influence of the Gulf-stream, 

 probably passing between the Cape- Verd Islands and the mainland of 

 Africa. Besides algse, the portions of this mass picked up by Capt. 

 Mitchell and examined by Dr. Dickie contained, amongst other sub- 

 stances, fruits, seeds and " seedling plants several inches long, aU 

 with a pair of cotyledons, roots, and terminal bud, quite fresh"*. 

 With regard to those American genera represented chiefly in Eastern 



* It may require, however, as suggested by Dr. Hooker, some further evi- 

 dence to show that this green mass might not as well have been brought down 

 from some African as from some American river. 



