THE ROMNEY FORMATION OF MARYLAND 367 



have generally been divided into the Marcellus shale and the Hamil- 

 ton beds. Professor Williams compiled a list of twelve species for 

 the Tropidoleptus fauna which he called the "standard list of domi- 

 nant species for the New York-Ontario province." Another list 

 was also compiled, which he called a "revised list of dominant 

 species of the Hamilton formation of eastern New York and Penn- 

 sylvania, as expressed in 183 faunules," which contained the twelve 

 species given in the standard list and four additional ones. All of 

 these sixteen species occur frequently in the Hamilton beds of Mary- 

 land. 



Professor Williams, after an examination of the preliminary lists 

 from the Hamilton beds of Maryland, published the following state- 

 ment: 



In the list furnished me by Professor Prosser there appear 132 entries, 91 of 

 which are positive identifications. Among the latter are found all of the dominant 

 species of the Tropidoleptus carinaius fauna, as estimated from the New ^^ork 

 statistics. This is sufficient to estabhsh the extension of the Tropidoleptus fauna, 

 in its integrity, as far south in the Appalachian trough as Maryland.^ 



Other facts brought out in the Maryland Devonian report by Dr. 

 John M. Clarke and the writer apparently show that the Hamilton 

 beds of Maryland are succeeded by deposits and faunas similar to 

 those succeeding the Hamilton of New York, and therefore it may 

 be concluded that the deposits of the Hamilton beds from New York 

 to West Virginia were brought to a close at about the same geological 

 time. 



EUROPEAN EQUIVALENTS. 



The early attempts at correlating the Devonian rocks of the United 

 States with those of Europe dealt only with the formations found in 

 New York, which, in fact, has generally been the custom down to 

 the present time. In 1842 Conrad published the statement that 

 "the Ithaca group, Chemung group, and the Old Red Sandstone 

 near Blossburg, in Pennsylvania, constitute the equivalents of the 

 Devonian system as developed in Europe," and contain a number 

 of fossils characteristic of European Devonian strata.^ The same 

 year Vanuxem stated that the last three groups of the "Erie Division" 



1 Bulletin No. 210, U. S. Geological Survey, p. 67. 



2 Journal of the Academy of Natural Science, Philadelphia, Vol. VIII, p. 232. 



