230 m:\v yokk stati-: miskum 



liMvr \\;iii(l('i'c(l into llic slialloNN' waters wluM'e Schohario sodi- 

 nu'iil was deposit in;^; 11h\v may liave, on ilie oilier band, eonio 

 in from som<' source, northeast or southeast, as yet unknown 

 to us. and lieiuc he rehited ancestrally to similar foi'ius of the 

 ovei'lyinj^- Onondajia limestone. l*i-es( nl e\idence seems to favor 

 the former conclusion without dispara^'enient to the ♦••enetic re- 

 lations of these cephalojiods to those of the Onondaga. It seems 

 justiliable however to assert that the fauna of the ()nondji<2:a 

 period as a whole, with its noteworthy coral, trilohite, cephalo- 

 ]i()d and f»astropod facies unequally devcdoju'd locally, is ;i com- 

 jtlex cono-eries, lar«iely from the western reaches of the Ap- 

 palachian j^ulf, but fre(dy inoculated with elements genetically 

 from the northeast. Tlie latter may have come in directly, 

 geographically and genetically, through the Oriskany province 

 of eastern New York or indirectly into the western limestones, 

 after migration from New York southward to the end of the 

 barrier and thence into the heart of the gulf. The latter seems 

 specially probable of the gastropod element. 



As the eastern w^aters cleared, the new fauna could migrate 

 eastward and so become the Schoharie fauna. At this time a 

 channel which extended northward along what is now^ the 

 Connecticut valley and thence b}' way of the St Lawrence 

 to the North Atlantic formed an outlet for the Onondaga sea 

 to the northeast. Since black mud strata w^ere deposited in this 

 channel till Schoharie time, no migration of pure water species 

 from the Atlantic could take place till just before the beginning 

 of Onondaga time. But with this channel open, Eurasian types 

 which had migrated along the shore of "Atlantis", a North 

 Atlantic continent, could enter the Misisissippian sea of eastern 

 North America. Schuchert believes that a portion of the Onon- 

 daga fauna at least came into the interior sea by this channel, 

 while another jiortion came from the Brazilian region by way • 

 of the southern oi- Indiana channel. It seems not unlikely that 

 the cephalo]iod element of the Schoharie entered the A])])alachian 

 gulf fi-oiii (lie noitlieast by the Connecticut channel, and mi- 

 grated westwai'd. a]>iiearing (Mther as the same species or in 

 modified foiiii ill I lie Onondaga of the western I'cgion. The same 

 tiling appears to be true of the trilobites, though some as 

 C a 1 y III 111 e n e p 1 a I y s ajijiear earlier or at the same time in 



