BUFFALO SOCIETY OF NATUEAL SCIENCES 215 



Pittsford to Bertie time, one or several rivers must have occupied ap- 

 proximately the same position, so that the Pittsford and Shawangunk 

 faunas could escape into the estuaries when the Salina sea became too 

 salt, and could remain there in the brackish water part of the estuary 

 until Bertie time, when they appeared in two localities, at Buffalo, 

 75 miles west of Pittsford, and around Herkimer, 130 miles east of 

 Pittsford. Taking up the first condition, we are confronted with a 

 grave difficulty if we try to think of the Pittsford and Shawangunk 

 fauna remaining in the Salina " lagoon" or at the mouths of estuaries 

 flowing into that inland body of water during Vernon, Syracuse, and 

 Camillus time, for it is evident that we must consider the Pittsford- 

 Shawangunk eurypterids as the ancestors of those found in the Bertie, 

 if we believe in this estuarine theory. In the succeeding pages, where 

 I shall consider every species of eurypterid as an entity and as a mem- 

 ber of a faunule, unless it be an isolated form, and where I shall take 

 up the possible modes and routes of migration of species and of fau- 

 nas, I shall show that the Pittsford- Shawangunk eurypterids were 

 not the ancestors of the Bertie forms, and therefore the first condition 

 which I mentioned at the beginning of this paragraph as a logical de- 

 duction from the " lagoon-estuary " theory is impossible, in which case 

 it would appear that the Bertie eurypterids had no ancestors. Let us 

 suppose, however, for the sake of argument, that the Pittsford-Sha- 

 wangunk fauna did constitute the ancestral stock for the Bertie fauna 

 and that in the dry and at times uncomfortably saline conditions of 

 Salina time the eurypterids left their lagoon and went into the estua- 

 ries and even part way up the rivers, seeking proper salinity of water; 

 then we should look for estuarine deposits of mud or perhaps coarser 

 elastics in the Salina of central and western New York, and for the re- 

 mains of marine organisms which are characteristic of such deposits. 

 (For criteria of estuarine deposits see p. 77 above.) But we search 

 in vain for estuarine, or delta, or flood-plain deposits in that region. 

 Following upon the Pittsford are the Vernon barren red shales with 

 their evidences of subaerial deposition with thorough oxidation 

 (Grabau, 84, 86a, 87), and then the Syracuse salt deposits. All of 

 this has been discussed before, and the evidence is clear that there 

 existed no estuaries in the area under question in which the early 

 Siluric eurypterids might have sought refuge. Thus, descendants of 

 early Salina "lagoon" species had no place of retreat during later Sa- 

 lina time, and must have perished of drought, and we see that the 

 Bertie eurypterids were doubly deprived of ancestors if they had to 

 depend upon the Pittsford-Shawangunk fauna. 



