274 ON THE ORIGIN OF SPECIES 



I cannot see that it would be an insuperable difficulty 

 on my theory, unless it could likewise be shown that 

 the species of this group appeared suddenly and simul- 

 taneously throughout the world at this same period. 

 It is almost superfluous to remark that hardly any 

 fossil-fish are known from south of the equator ; and 

 by running through Pictet's Paleontology it will be 

 seen that very few species are known from several 

 formations in Europe. Some few families of fish now 

 have a confined range ; the teleostean fish might for- 

 merly have had a similarly confined range, and after 

 having been largely developed in some one sea, might 

 have spread widely. Nor have we any right to suppose 

 that the seas of the world have always been so freely 

 open from south to north as they are at present. Even 

 at this day, if the Malay Archipelago were converted 

 into land, the tropical parts of the Indian Ocean would 

 form a large and perfectly enclosed basin, in which 

 any great group of marine animals might be multi- 

 plied ; and here they would remain confined, until 

 some of the species became adapted to a cooler climate, 

 and were enabled to double the southern capes of 

 Africa or Australia, and thus reach other and distant 

 seas. 



From these and similar considerations, but chiefly 

 from our ignorance of the geology of other countries 

 beyond the confines of Europe and the United States ; 

 and from the revolution in our palaeontological ideas 

 on many points, which the discoveries of even the last 

 dozen years have effected, it seems to me to be about 

 as rash in us to dogmatise on the succession of organic 

 beings throughout the world, as it would be for a 

 naturalist to land for five minutes on some one barren 

 point in Australia, and then to discuss the number and 

 range of its productions. 



On the sudden appearance of groups of Allied Species 

 in the lowest known fossiliferous strata. — There is another 

 and allied difficulty, which is much graver. I allude 

 to the manner in which numbers of species of the same 



