BUFFALO SOCIETY OF NATURAL SCIENCES 23 1 



Baltic area that the latter for a long time was identified with the 

 former. Schmidt was the first to suggest that the differences between 

 the two species were only geographical variations arising through 

 migration. With this idea Clarke and Ruedemann have concurred. 

 In fact, they point out in many places the close similarity between 

 the Bertie and Oesel fauna, and especially between the two common- 

 est species in both, E. remipes and E. fischeri. Now, if the Bertie 

 fauna was an estuarine one, preserved from Pittsford time in various 

 brackish water bodies, when and how did migrations take place to 

 the Baltic sea of the Upper Siluric? The answer will undoubtedly be 

 that the members of the marine stock in the Lower Siluric which were 

 not caught or did not voluntarily seek refuge in the "lagoon" or 

 remnant of Niagaran sea in New York State, migrated along the 

 shore of Atlantica, passing from estuary to estuary until they reached 

 the island of Oesel. This might seem like a very happy solution, if 

 the British Isles did not intervene between America and Oesel, and 

 if they did not have a very clear record to show that no such migra- 

 tion took place. In the discussion of the faunas of the various 

 Palaeozoic continents, given below, it will be shown that the Wen- 

 lock, Ludlow, and Lanarkian faunas of Great Britain offer no indica- 

 tions of migrations along the neritic zone during those periods and 

 that in many cases new genera as well as new species arose suddenly 

 without, apparently, having a genetic relationship to corresponding 

 taxonomic units in other countries. 



Since the assumption that the early Salina eurypterids lived in a 

 - "lagoon more or less cut off from the sea," leads to such difficulties, 

 we must seek another theory. Let us assume that they lived in the 

 rivers, and draw the logical deductions. It has been shown from their 

 lithogenesis that the Pittsford and Shawangunk deposits must have 

 been derived from Appalachia, while the Bertie was derived from 

 Atlantica. Rivers, whether existing at the same time or at different 

 geological periods, would carry related forms if coming from the same 

 continent, but unrelated or only distantly related forms if coming from 

 two different continents. Thus the Pittsford and Shawangunk euryp- 

 terids would be near relatives to say the least ; while the fact that the 

 larval forms from the latter are merely the young of those from the 

 former is all the more according to our expectations. 3 Likewise the 

 absence of close relationship between the Shawangunk and the Bertie, 



3 It should be noted here that the adult individuals of the Shawangunk were preserved only as 

 unrecognized fragments, the young forms alone, by virtue of their small size, escaping the destruction 

 which was meted out to their progenitors, as was discussed on p. 101. 



