BUFFALO SOCIETY OF NATURAL SCIENCES 229 



only by the consideration of former land and sea connections or bar- 

 riers, it is necessary in discussing the Bertie faunule to take into ac- 

 count the palseogeography of preceding periods and the distribution 

 of earlier faunas. 



It has seldom been our good fortune to find two succeeding eu- 

 rypterid faunas in the same locality, so that not many opportunities 

 have been available to trace direct descent; but New Yo:k State has 

 been favored in this respect and too much importance can not be at- 

 tached to the relational values of the Pittsford, Shawangunk, and 

 Bertie faunas. 



Comparison of the Pittsford, Shawangunk, and Bertie faunas. As 

 a matter of fact, the Bertie fauna in neither "pool" shows any very 

 marked affinities with the Shawangunk fauna or with the Pittsford, 

 with one exception, already noted, and more fully discussed, below. 

 Of the fourteen species known from the Bertie, there are only four 

 in which even a slight resemblance can be seen to the upper Niagaran 

 forms, and this resemblance in each case (with the one exception 

 noted) is so very small that it cannot be said to constitute a proof of 

 genetic relationship. For instance, Dolichopterus (?) testudineus 

 from the Herkimer "pool" is represented by a single uncompressed 

 carapace which in outline, general proportions, and the position of 

 the eyes is quite similar to one of the specimens of D. otisius in the 

 Shawangunk. But while this general resemblance to one carapace 

 of the Shawangunk form has been pointed out by Clarke and Rue- 

 demann, attention should also be called to the fact that it is very dif- 

 ferent from one of the best preserved, most typical Shawangunk 

 carapaces of the same species. The sub-elliptical shape of D. testu- 

 dineus is quite distinct from the sub-quadrate one of D. otisius, and 

 it does not seem to the author that any genetic relation is indicated 

 between these two forms. To overcome this difficulty of lack of rela- 

 tionship between the Shawangunk and Bertie faunas, it might be ar- 

 gued that the latter was derived from the Pittsford alone. But the 

 only species in the latter which is supposed to have even a semblance 

 of relationship to a Bertie species is Pterygotus monroensis which has 

 been compared with P. cobbi. The former species was founded on a 

 single carapace, and two other fragments are now known. One of 

 these is the fragment of a free pincer of the chelicera which is thought 

 to belong to P. monroensis. This shows one long, rounded tooth at 

 the extremity, then a short tooth, another long tooth but not so long 

 as the first, four short teeth alternating in size, followed by a long 



