BUFFALO SOCIETY OF NATURAL SCIENCES 55 



of the Early Vertebrates" gives a philosophical discussion of the 

 question which is extremely interesting and suggestive, though not 

 backed up by much data. He calls attention to the fact that euryp- 

 terids and fishes are found associated in the Ludlow (Upper Siluric) 

 of England, in the Island of Oesel in the Russian Baltic, in Podolia, 

 Russia, in Galicia, and in the Waterlime group of North America. 

 "The physical conditions in all these cases seem to have been pe- 

 culiar," he continues, "and in the case of the Waterlime group they 

 were singularly so, for they permitted a host of these large Euryp- 

 terids and other Crustaceans to flourish in seeming luxuriance, while 

 only a meagre and pauperate marine fauna found an occasional 

 entrance into the series. The conditions seem to have been con- 

 genial to the fish and Eurypterids, but not to a typical marine fauna" 

 (32, 401, 402). The association- of eurypterids and fishes in the Old 

 Red sandstone where marine life was only occasional and meagre 

 does not, as Chamberlin points out, imply prevalent marine condi- 

 tions, for the Old Red and its homologues are the deposits of fresh 

 water, and yet both the fishes and eurypterids found congenial con- 

 ditions of life there. Chamberlin, recalling that fishes and euryp- 

 terids are found both earlier and later than the Devonic in marine 

 deposits, puts the following question : "Were the fishes and eurypterids 

 primarily marine and later became adapted to fresh water, or were 

 they primarily fresh water forms which were occasionally carried out 

 to sea and which later became adapted to salt water?" He reminds 

 us that we are always in the habit of considering all life at first marine, 

 then terrestrial, but, though this is true in general, the idea should 

 not be held to with too great tenacity in every case. That the 

 eurypterids may well furnish an example of an exceptional case is 

 shown by various lines of evidence which Chamberlin cites. First, 

 of the dozen genera of eurypterids known in 1900 only two or three 

 of the least well known are without associations with formations 

 regarded as fresh water; secondly, he says: "The relics found in marine 

 sediments may be attributed to transportation from the land just as 

 is one in the case of terrestrial plants and land insects not infre- 

 quently found in marine beds; but transportation in the opposite 

 direction cannot be assigned" (32). One may, however, take excep- 

 tion to this last stat ment, for many marine forms migrate up rivers 

 in the spawning season, as for instance, the crabs which go up the 

 Hudson as far as Albany; and there are many marine molluscs which 

 become adapted to conditions in rivers and may even in time migrate 



