66 ZOOLOGICAL GEOGRAPHY. [PART m. 



ductiveness, but this is, no doubt, partly due to our knowledge 

 of Cuba and Jamaica being much more complete than of 

 Havti. The species of resident land-birds at present known are 

 as follows : 



Cuba 68 species, of which 40 are peculiar to it. 



Hayti 40 17 



Jamaica 67 41 



Portonco 40 15 



Lesser Antilles 45 24 



If we count the peculiar genera of each island, and reckon 

 as (J) when a genus is common to two islands only, the 

 numbers are as follows : Cuba 7j, Hayti 3J, Jamaica 8J, 

 Portorico 1, Lesser Antilles 3J. These figures show us, that 

 although Jamaica is one of the smaller and the most isolated of 

 the four chief islands, it yet stands in the first rank, both for the 

 number of its species and of its peculiar forms of birds, and 

 although this superiority may be in part due to its having been 

 more investigated, it is probably not wholly so, since Cuba has also 

 been well explored. This fact indicates, that the West Indian 

 islands have undergone great changes, and that they were not 

 peopled by immigration from surrounding countries while in 

 the condition we now see them ; for in that case the smaller 

 and more remote islands would be very much poorer, while 

 Cuba, which is not only the largest, but nearest to the mainland 

 in two directions, would be immensely richer, just as it really 

 is in migratory birds. 



The number of birds common to the four larger islands is 

 very small probably not more than half a dozen ; between 20 

 and 30 are common to some two of the islands (counting the 

 Lesser Antilles as one island) and a few to three ; but the great 

 mass of the species (at least 140) are confined each to some one 

 of the five islands or groups we have indicated. This is an amount 

 of isolation and speciality, probably not to be equalled else- 

 where, and which must have required a remarkable series of 

 physical changes to bring about. What those changes probably 

 were, we shall be in a better position to consider when we have 

 completed our survey of the various classes of land animals. . 



