of the Galapagos Archipelago. 261 



further conclusions, the numbers representing the relationship of the peculiar 

 and non-peculiar plants of each islet to one another being small. There is 

 however one point which demands a notice, and that is, the obvious relation 

 between the distribution of the peculiar species over the four islets in ques- 

 , tion and the direction of the easterly current. Chathain Island being situated 

 east of the group, it follows that the current can never transport insular spe- 

 cies to it : on the other hand, Albemarle, on the west, lies directly in its 

 course. Now, excluding the American plants altogether, we have the follow- 

 ing evidence of the western islands being peopled by colonists from the east- 

 ern; shown by the proportion each islet contains of the Galapageian species 

 found on others. 



Chatham Island ; its Galapageian species found on other islets are to whole florula as 1 : 5"0. 

 James Island ; its Galapageian species found on other islets are to whole florula as 1 : 4'8. 

 Albemarle Island; its Galapageian species found on other islets are to whole florula as 1 : 3'9. 

 Charles Island ; its Galapageian species found on other islets are to whole florula as 1 : 3"1. 



The amount of difference between the islets is, as I have stated above, 

 mainly specific, and is apparent in no less than fifty-eight of the peculiar spe- 

 cies of the archipelago, which thus represent one another, and for whose names 

 I would refer to the catalogue of the species already before the Society. 



The above remarks I have confined to the most salient features of the Ga- 

 lapageian Flora, and such as I would hope may not be materially affected by 

 future investigations in this most interesting archipelago. There are others 

 which appeared prominent, it is true, but which required for their confirma- 

 tion more ample collections than have hitherto been formed, and these I have 

 suppressed until materials for their establishment shall be forthcoming*. 



Royal Gardens, Kew, November 1846. 



* The following described species, collected by the late T. Edmonstone, Esq. in Charles Island, 

 together with one undescribed found by Mr. Darwin in Chatham Island, were omitted in my enumera- 

 tion, but are included in the foregoing remarks. 



1. Digitaria serotina, Michx. — 2. Alternanthera radicata, n. sp. (See below). — 3. Heliotropium In- 

 dicum, L. — 4, 5. Clerodendron, species 2 (exemplaria manca). — 6. Hyptis capitata, Jacq. — 7. Varronia 

 dasycephala, Desv. — 8. Nicotiana, sp. — 9. Physalis, sp. — 10, 11. Solani, species 2. — 12. Calystegia 

 Soldanella, R. and S. — 13. Wedelia frutescens, Jacq. — 14. Spilanthes Acmella, L. — 15. Eupatorium .' sp. 

 — 16. Baccharis pilularis, DeC. — 17. Composita. — 18. Galactia, n. sp. — 19. Poindana pulcherrima, L. 



2 M 2 



