234 THE HABITAT OF THE EURYPTERIDA 



Further corroboration is offered by Van Ingen's discovery in 

 Oneida county already referred to. In the concretionary block 

 obtained from that locality and determined from lingulas and 

 orbiculoideas in it to come from dark gray shales with inter- 

 calated waterlimes and dolomite beds 21 feet below the base 

 of the red Vernon shale, 5 were found three carapaces and frag- 

 ments of a eurypterid, which Clarke and Ruedemann have named 

 Eusarcus vanifigeni. They state that "the outline of the body 

 the visual surface .... the appendages, so far 

 as seen, are like those of E. scorpionis. The tergites and stern ites 



have the form and relative dimensions of E. scorpionis 



The ornamentation is that of E. scorpionis, but the scales are smaller 

 and more, clearly arranged" (39, 420, 421). It is also somewhat 

 related to E. cicerops from the Shawangunk, but the relation is generic 

 rather than specific. That this species of Eusarcus, more closely 

 related to a species in the Bertie than to a contemporary species in 

 the Pittsford, should be found in the waterlime facies of the Pittsford 

 rocks in a region but a few miles distant from the mouth of the 

 subsequent Herkimer river, is a most unusual corroboration of our 

 theory. It is exactly what could have been prophesied. How such 

 an occurrence is to be explained on the lagoon theory is puzzling. 



If the river hypothesis is the correct one it must account for the mi- 

 gration of the eurypterids from the Buffalo region to the Baltic during 

 the Salinan or early Monroan. If we assume the existence of two 

 rivers flowing from the rather low and flat limestone-covered country 

 to the north, into a sea which had its shore extending through New 

 York, as indicated on the map (fig. 8), it would not be difficult to 

 understand that the shed exoskeletons of arthropods inhabiting the 

 waters of these rivers and occasionally dead or even living individuals 

 would be carried down stream, and become embedded in the fine lime 

 sediment of the two neighboring deltas or in the interstream areas. 

 Probably the eurypterids themselves were seldom carried down to 

 the debouchures, since it is their molted exoskeletons which are gen- 

 erally found. To account for the similarity of the Buffalo and Her- 

 kimer faunules, it is necessary to postulate the interfingering of the 

 headwaters of the Bertie and Herkimer rivers. The physical and 

 faunal conditions would then be analogous to those existing at the 

 present time in the Columbia and Missouri rivers, as outlined on 



5 1 shall refer to these shales hereafter as the Farmer's Mills shales, from the locality near which 

 they were found. 



