BUFFALO SOCIETY OF NATURAL SCIENCES 211 



understand that a fauna may be made up of individuals which show a 

 fairly close relationship with faunas in neighboring areas, but may 

 contain one species which is identical or nearly so with a species in a 

 fauna three thousand miles distant. If these were marine fossils we 

 could not understand such a thing, because marine faunas show whole 

 groups of species in one region related to groups in another, and con- 

 temporaneous marine deposits in the path of migration show similar 

 related groups. But the routes of migration for river forms would 

 almost never be shown to us in the rocks, because rivers in their up- 

 per and middle portions degrade and would continually be carrying 

 away the traces of their history which would be recorded only in del- 

 tas or flood plains. Thus, contemporaneous and related fluviatile 

 faunas would appear geographically at the outer ends of the spokes 

 of a great wheel which has its hub at the centre of dispersal. The 

 remains of synchronous faunas would of necessity appear scattered 

 over the face of the earth, without any apparent connection; a fact 

 which would be inexplicable if the faunas were interpreted as marine. 

 The only way to solve the problem of the distribution of those forms 

 would be through a study of the palaeogeography of the period in 

 which they occurred and of all preceding periods in so far as was 

 possible. 



When stratigraphers come fully to appreciate the value of conti- 

 nental deposits and faunas, they will have taken a big step toward 

 the unravelling of the palaeogeography of our earth. No one would 

 attempt to restore the conditions of land and sea in the Tertiary with- 

 out making use of the migrations of mammals and other terrestrial 

 organisms, for it is evident that while a study of marine faunas will 

 show the position of the oceans and epicontinental seas in any period, 

 the exact configurations of the continents, the exact location of land 

 barriers and connections can only be determined by the migrations 

 of the animals and plants living on the land or in the rivers. This 

 applies with as great truth to the Palaeozoic as to the Tertiary, and 

 while the aid of plants cannot there be invoked until the end of the 

 period, I hope to show before concluding this paper that the euryp- 

 terids will be of vast service in helping to locate Palaeozoic rivers and 

 routes of migration from one continent to another. 



