TRANSACTIONS OF SECTION C. 



707 



before you my quotations of the most authoritative writers have been made less 

 for the purpose of showing' reverence than of expressing scepticism. My reason 

 for calling attention to Professor Huxley's views is different. I entirely agree 

 -with them ; but there is, I think, something to be added to them. There is, I 

 believe, an additional distinction between land and marine faunas that requires 

 notice, and this distinction is one of very great importance and interest. It 

 appears to me that at the present day the difference between the land-faunas of 

 •different parts of the world is so vastly greater than that between the marine 

 faunas, that if both were found fossilised, whilst there would be but little difficulty 

 in recognising different marine deposits as of like age from their organic remains, 

 terrestrial and fresh-water beds would in all probability be referred to widely 

 differing epochs, and that some would be more probably classed with those of a past 

 period than with others of the present time. 



I had proposed to enter at some length into this subject, and to attempt a 

 sketch of the present state of our knowledge concerning the distribution of terres- 

 trial and marine faunas and floras. But I found that it was impossible to do 

 justice to the question without making this address far longer than is desirable, 

 and I have already taken up more time than I ought to have done. I can there- 

 fore only treat the subjects very briefly. 



As you are doubtless aware, the most important work upon the distribution of 

 terrestrial animals yet published is that of Mr. Wallace. He divides the earth's 

 surface into six regions— Palsearctic, Ethiopian, Oriental, Australian, Neotropical, 

 and Nearctic. Some naturalists, with whom I am disposed to agree, consider 

 Madagascar and the adjacent islands a seventh region, and it is possible that one 

 or two other additions might be made. 



These regions are essentially founded on the distribution of vertebrata, 

 especially mammals and birds, and the following table, taken from Wallace's lists, 

 shows the percentage of peculiar families of vertebrata and peculiar genera of 

 mammalia in each region, mammalia being selected as more characteristic than 

 birds and better known than reptiles, amphibians, or fishes : — 



The marine mammals and reptiles are too few in number to be compared with 

 the land-fauna, but whales, porpoises, seals, sireniaus, turtles, and sea-snakes are 

 for the most part widely diffused. The best class of the vertebrata for comparison 

 is that of the fishes, and some details taken by Wallace from Giinther's ' British 

 Museum Catalogue ' are very important. The whole class is divided into 116 

 families, of which 29 are exclusively confined to fresh water, whilst SO are typically 

 marine. Of these 80 no less than 50 are universally, or almost universally, dis- 

 tributed, whilst many others have a very wide range. Four families are con- 

 fined to the Atlantic and 13 to the Pacific Ocean, whilst a few more are 

 exclusively southern or northern. About 63 are found in both the Atlantic and 

 Pacific. 



Now, of the 29 fresh-water families 15, or more than one-half, are confined 

 «ach to a single region, 9 are found each in two regions, 2 in three regions, and 

 the same number in four; one only {Cyprinidce) is found in five. regions, whilst 

 not one is met with in all six. It is impossible to conceive a greater contrast : 

 50 marine families, or 62-5 per cent., have a world-wide distribution, whilst not a 



