82 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



8. Indian (India and S.E. Asia, Malay Archipelago, Papuasia, 



Northern Australia, and Polynesia). 



9. Tropical American. 



10. Cape of Good Hope (a small region near the Cape). 



11. Australian (Australia south of the tropics and Tasmania). 



12. Kovo-Zelanian. 



13. Andian (Tropical Andes, Chili, and the Argentine Eepublic). 



14. Antarctic (southern extremity of America and antarctic 



islands) . 



It is sufficient to point out that, in both these systems, the 

 greater part of the two regions of the earth which in mammalia 

 exhibit the greatest diversity, the Oriental and Australian, are 

 combined into one region. 



In many respects the distribution of plants accords very well with 

 that of land-moUusca. 



If now we proceed to consider, as a whole, the geographical dis- 

 tribution of such different subdivisions of the animal kingdom as 

 have been noticed, it will be observed that the mammals, batrachia, 

 freshwater fishes, and land-mollusca appear, at all events in the 

 opinion of the naturalists who have paid especial attention to the 

 subject, to approach the passerine birds in distribution more than 

 the reptiles or plants do. But, as I have pointed out, the fresh- 

 water fishes and land- and freshwater moUusca are heterogeneous 

 groups made up of families and genera of various origin, and having 

 very often, probably as a rule, a distribution not agreeing with each 

 other in the smallest degree. Under the circnmstances it is easy to 

 see how the conflicting distribution of difi:erent families amongst 

 such groups as land-shells or freshwater fishes will produce a general 

 result, in which the only dominant feature will be trivial generic 

 or subgeneric distinctions, closely connected with the modern distri- 

 bution of land and water. The batrachians to some extent are open 

 to the same remark, for they consist of three orders, Anura, Cau- 

 data, and Apoda, having but little affinity and almost certainly 

 of widely different antiquity. The reason why batrachia agree 

 on the whole with passerine birds and mammalia better than rep- 

 tilia, is not improbably that anurous batrachia (frogs and toads), 

 the only important living order, are of comparatively recent deve- 

 lopment. Placental mammalia, too, may be less ancient than the 

 reptilian orders, at all events in the present land area. There is, 

 ill short, a strong reason for believing that the more recently deve- 



