k 



)ll 



K- 



a- 



« 



i 



V 



15: 



Ni 



ire 





4 



Ch. XLI.] 



REFERENCE TO THE ORIGIN OF SPECIES. 



421 



others were sown, and wlien they had germinated 



than seven individuals belonging to at least two kinds of 



X ■ 



A locust of the migratory species 



oTasses were obtained. 



blown from tlie coast of Africa was taken on one occasion by 



Mr 



somewhat farther than is Madeir 



some 



from Africa. The same naturalist observed in 1867 

 mud adhering firmly to the foot of a woodcock, which 



weighed when dry nine grains 



He 



extracted from it the 

 germinated. This fact 

 the colonisation of new islands by 

 plants, for of all orders even of wading birds the woodcocks 

 are nerhans the most mip:ratory, and there is scarcely a remote 



much light on 



sometimes 



When we compare 

 pelagos — that of the 



Madeiras for exam 



with that of the 



_^^^^ Islands, the difference in the number of indigenous 



r 



species and in the proportion of plants common to the 

 nearest continent is truly marvellous. In the British area 

 there is only a single peculiar plant of the pha^nogamous 

 class, one of the orchids, Spiranthes gemmipora^ out of 1,500 



species 



Madeiras 



numerous 



British. On the other hand, all the British plants are species 



common 



North American 



In the Ma 



above mentioned, and a 

 caulon septangulare. 



Landshells. — I have reserved to the last my comments 

 on the landshells, as their geographical distribution in 

 the Atlantic islands is more singular and instructive than 

 that of any other class of living beings, 

 deiran archipelago especially, as was long ago pointed out 

 by the Rev. E. T. Lowe, CA^ery island has its distinct species, 



r 



and the whole fauna differs almost entirely from that of 

 every other archipelago as well as from that of Europe and 

 Africa. Moreover, it is when we contemplate these air- 



le contrast between the 



mollusks 



V 



Atlantic and British islands to have reached its climax; 

 for in Great Britain no one of the different islands is cliarac- 



