CH. IV] KERGUELEN AND FERNANDO NORONHA. 207 



On the other hand, Madagascar abounds in peculiar 

 forms, even of family rank, and certainly in numerous 

 cases of generic rank. This difference again is correlated 

 with physical conditions. Britain is separated from 

 France by scarcely 30 miles of sea, which is so shallow 

 that, as is stated, the dome of S. Paul's Cathedral in 

 London, if submerged anywhere in that sea, would stand 

 for the most part clear above the waves. On the other 

 hand Madagascar lies 250 miles from the African coast, 

 from which it is separated by an ocean varying in depth 

 from 1,000 to 1,500 fathoms. The inference is that the 

 separation between Britain and Europe is of much later 

 date than that between Madagascar and Africa. More 

 time would in all probability elapse between the scooping 

 out of the deep channel which divides Madagascar from 

 Africa, than of the narrow and shallow Straits of Dover. 



Oceanic Islands. 



The four oceanic islands again possess faunas which are 

 not absolutely the same in character. Fernando Noronha 

 and Kerguelen contrast with the Galapagos and the 

 Sandwich Islands by reason of the poverty of their fauna. 

 They differ from each other also. Kerguelen has a poor 

 fauna, hardly if at all richer than that which populates 

 Fernando Noronha, but the number of peculiar types is 

 larger and more marked ; more marked because the types 

 are to a considerable extent of peculiar genera. This would 

 tend to prove that Kerguelen is older as an island than is 

 Fernando Noronha; more time has elapsed since it was 



