REPORT OP THE STATE PALEONTOLOGIST 1901 655 



est depression of the Skunnemunk trough and the Cumberland { 

 basin was to the south of New Jersey, and there permitted the 

 Atlantic during the Marcellus to spread its fauna across the 

 Chilhowee barrier into the Mississippian sea. 



These deposits were laid down in waters occupying a trough 

 lying east of the Appalachian valley trough, and hold, as do also 

 the equivalent sediments of the Cumberland basin, faunas having 

 different aspects from those of the Devonic west of the Cincin- 

 nati axis. The communication between these basins or troughs 

 and the Atlantic was, we believe, effected by channels corre- 

 sponding in position to the present Chesapeake and Delaware 

 bays. We believe further that it was through these channels 

 that the Skunnemunk trough and the eastern Mississippian sea, 

 the latter covering Virginia, Maryland, Pennsylvania and New 

 York at the time, received its Marcellus accessions. These 

 migrants are now found mixed together with the indigenous 

 early Hamilton faunas as far west as western Ontario (Thed- 

 ford). Some of these European accessions are Strophalosia, 

 Liorhynchus, Tropidoleptus, Tentaculites, Styliolina, Actinop- 

 teria, Pterochaenia, Bactrites and Tornoceras. 1 



Our derivation of this fauna from Europe by way of the Atlan- 

 tic goes further than Dr Clarke's views. He regards it " as an 

 invader from the southeast along the inner or Appalachian face 

 of the interior sea." 2 The Marcellus is well developed about 

 Cumberland Md., and south to about central Virginia, where this 

 formation pinches out. We therefore conclude that the invasion 

 from the Atlantic was somewhere in the Chesapeake bay region. 

 The bulk of the Marcellus fauna is however indigenous to the 

 eastern Mississippian sea and is a development out of the 

 Onondaga. 



*We should not have been able to make these statements, had we not 

 the excellent work of Dr Clarke on the Marcellus faunas. These papers 

 are the following: N. Y. state geol. 4th an. rep't 1884. 1885. p. 11; N. Y. 

 state mus. 42d an. rep't. 1889. p. 406-97; N. Y. state mus. Bui. 49. 1902. 

 p. 115-38 and Miss Wood's paper following on p. 139-81. 



2 lb. p. 115. 



Marcellus 

 nvasion 



