Geographical Distrihiition of Animals. 211 



Cape Cod in Massachusetts, where many marine species meet 

 from either side, but do not pass the boundary. 



In general, the boundaries of zoological provinces which are 

 not insular, are more indefinite, in proportion as we include a 

 greater part of the animal kingdom in one set of provinces. 



18. Analogues are usually more numerous in adjacent or 

 approximate zoological provinces than in those which are 

 remote from each other. Thus there are more analogues in 

 the Caribbean and Panama marine provinces than in the 

 Caribbean and Indian Oceans. The terrestrial faunae of Cuba, 

 St, Domingo, Porto Rico, and Jamaica, contain many more 

 analogues than either of these islands compared with the 

 Philippine Islands. 



Areas of Genera and of more Comprehensive Groups. 



19. The proposition respecting specific areas (§ 1), may be 

 applied to groups more comprehensive than species, but with 

 more and more qualification, as the groups are more and more 

 comprehensive, until at length it fails entirely; and the areas 

 become greater, until at length the whole planet becomes a 

 single area. 



Thus many genera inhabit each a single area, as Cylindrella. 

 Some genera are chiefly restricted to a single area, as Clausilia.^ 

 Others are cosmopolite. Some families, a few orders, and 

 at least one class (Reptiles) are restricted each to one area. 

 Tropical regions constitute a single area for several natural 

 families and orders in both the vegetable and animal kingdoms. 

 The area of the Cypraeidte consists of the tropical zone with 

 adjacent parts of the temperate zones. The area of the class of 

 Reptiles comprises all the warm and temperate regions of the 

 earth's surface. 



The vanishing point of this proposition is in the truism — 

 that the area of the whole animal kingdom is the whole of the 

 planet. 



* Sec article following, on the Clausilitc of America, by Thomas Blaiul, p. 224. 



