2 28 THE HABITAT OF THE EURYPTERIDA 



The Eurypterid Faunas or Atlantica. The eurypterid-bearing 

 formations which, mainly on lithological grounds, are thought to have 

 come from Atlantica are (i) Bertie, (2) Rondout, (3) Manlius (4) 

 Siluric waterlimes of Oesel, (5) Waterlimes of Gotland, (6) Wenlock of 

 Scotland, (7) Old Red sandstone. The faunas of these various forma- 

 tions will be taken up in detail with a view to determining the rela- 

 tions between individual species and between the faunas inter se. 



Of the above mentioned formations and their contained faunas, 

 the first three, which are North American, are quickly disposed of. 

 The Rondout waterlime has thus far yielded but a single species, and 

 this is the same as one from the Bertie, namely, Eurypterus remipes. 

 Similarly, only one species is known from the Manlius, a number of 

 specimens, for the most part poorly preserved, having been found in 

 various localities ranging from Albany, Herkimer, Madison andOnon 

 daga counties, New York, to Put-in-Bay,Lake Erie, where it occurs in 

 the stratigraphically older early Monroe beds. Only one specimen 

 has been found in which the abdomen is preserved, the remaining 

 occurrences being only of carapaces, and even these are often poorly 

 preserved. In outline of carapace and lack of ornamentation thereon, 

 this species more closely resembles E. brewsteri from the Arbroath pav- 

 ing stones than any form known from North America, though the simi- 

 larity to E. lacustris from the Bertie is not to be overlooked. Thus, 

 the only known eurypterid from the Rondout is the same as a species 

 from the Bertie, and the single species from the Manlius and the lower 

 Monroe shows affinities to one from the Bertie and to one from the 

 Old Red sandstone. With these two so easily dismissed, we may 

 turn to a detailed discussion of the Bertie fauna in which connection 

 it will be necessasy to establish the complete affinities of each species 

 by a detailed morphological and phylogenetic comparison with species 

 in preceding and contemporaneous faunules in America and Europe; 

 the centres of dispersion and the routes of migration must be care- 

 fully studied, and the possibilities of fluviatile and marine distribu- 

 tion must be weighed. More deductions can be drawn from the study 

 of the Upper Siluric faunas than from that of any other, because of 

 the abundant data available, the appearance of chronofaunasin widely 

 separated localities and the relative abundance of individuals and 

 species in several of the faunules. Because it is impossible to draw 

 correct deductions regarding the mode of distribution of organisms in 

 any one period from the observation of the distribution visible at 

 that time (see p. 208 above), and since the truth is to be arrived at 



