484 GEOGRAPHICAL DISTRIBUTION [CHAP. VI 



Letter 366 and some would be more liable than others to adhere to birds' 

 feet. But we know so very little on these points that it seems 

 to me that we cannot at all tell what forms would probably 

 be introduced and what would not. I do not for a moment 

 pretend that these means of introduction can be proved to 

 have acted ; but they seem to me sufficient, with no valid 

 or heavy objections, whilst there are, as it seems to me, the 

 heaviest objections on geological and on geographical distri- 

 bution grounds (pp. 387, 388, Origin^) to Forbes' enormous 

 continental extensions. But I fear that I shall and have 

 bored you. 



Letter 367 J. D. Hooker to C. Darwin. 



In a letter of July 3ist, Sir J. D. Hooker wrote, "You must not 

 suppose me to be a champion of continental connection, because I am 

 not agreeable to trans-oceanic migration . . . either hypothesis appears 

 to me well to cover the facts of oceanic floras, but there are grave 

 objections to both, botanical to yours, geological to Forbes'." 



The following interesting letters give some of Sir Joseph's difficulties. 



Kew, Aug. 4th, 1866. 



You mention (Journal^ no land-birds, except introduced, 

 upon St. Helena. Beatson (Introd. xvii) mentions one 2 "in 

 considerable numbers," resembles sand-lark is called " wire 

 bird," has long greenish legs like wires, runs fast, eyes large, 

 bill moderately long, is rather shy, does not possess much 

 powers of flight. What was it ? I have written to ask 

 Sclater, also about birds of Madeira and Azores. It is a 

 very curious thing that the Azores do not contain the (non- 

 European) American genus Clethra, that is found in Madeira 

 and Canaries, and that the Azores contain no trace of 

 American element (beyond what is common to Madeira), 

 except a species of Samcula, a genus with hooked bristles 

 to the small seed-vessels. The European Sanicula roams 

 from Norway to Madeira, Canaries, Cape Verde, Cameroons, 

 Cape of Good Hope, and from Britain to Japan, and also is, I 



1 Ed. in., or Ed. vi., p. 323. 



2 AZgialitis sanct<z-helen<z, a small plover " very closely allied to a 

 species found in South Africa, but presenting certain differences which 

 entitle it to the rank of a peculiar species " (Wallace, Island Life, p. 294). 

 In the earlier editions of the Origin (e.g. Ed. III., p. 422) Darwin wrote 

 that "Madeira does not possess one peculiar bird." In Ed. iv. 3 1866, 

 p. 465, the mistake was put right. 



