41 8 Evolution and Distribution of Fishes 



diverged, the Catostominae along one, the Cyprininae along 

 two northern and — what might now be called — extraconti- 

 nental lines, that extend in opposite directions. One was 

 the evidently wide landmass that — during late Cretaceous 

 and much, if not all of Eocene time — connected N. W. 

 America with a broad extension toward it of the Old An- 

 gara continent. 



Few species of Catostominae crossed this mass into 

 Siberia, or if once abundant, they are now indicated only — 

 so far as accurately known — by one or two species of 

 Catostomits. On the other hand the Cyprininae not only 

 effected an important migration thitherward, they evidently 

 spread westward into Siberia and southward into China, 

 Japan, India, and ultimately the E. Indian Archipelago, 

 as the genera Barbiis, SqiiaUoharbus, and Achilognathus 

 show. Now Barbus, with about 300 species, is the largest 

 genus of the sub-family, and is also known fossil from 

 mid and later Tertiary strata through S. E. Asia to central 

 Germany. 



But not a few genera — especially the tropical Asiatic 

 ones — doubtless evolved on that continent. Meanwhile 

 from E. America along the N. Atlantis landmass, an equal- 

 ly important migration set in toward W. Europe, probably 

 led by the genus Leuciscus, that has been reported from 

 Miocene rocks of N. America. In having upwards of 80 

 existing species, it is next to Barbus the richest in the family. 

 In addition to many that cover the N. American continent 

 down to Mexico, species are found in Britain, Holland, 

 Belgium, Germany, Switzerland, Spain, Austria, Italy to 

 Crimea, Asia Minor, and eastward to the Tigris. 



Abramis^ with a somewhat more restricted range, and 

 with fewer species, seems to have spread parallel to, but 

 along a line north of, that followed by Leuciscus. 



The above double and diverging migration on the one 

 hand into Asia, on the other into Europe, evidently resulted 

 in an occasional and ultimate meeting and interblending of 

 the two streams of fishes. This seems to have taken place 

 along a region that was alternately land and sea, and where 

 the Angara or Asian and the N. Atlantis masses approached, 

 and at times connected with each other. This ran approxi- 



