JS70.] '*^'i [Wiiichcll. 



heretofore been recognized in that part of the country. Further east, 

 however, where they become lithologically differentiated from the Che- 

 mung, they had long since been assigned a distinct position, both in Penn- 

 sylvania and New York. 



V. The Fauka of the Marshall Group presekts a Carbokiferous 



Aspect. 



I proceed in the next place to prove, on paleontological grounds, that 

 the Marshall group possesses close affinities with the carboniferous system. 

 These affinities are manifested in the presence of species identical with 

 recognized carboniferous fossils of America and Europe ; in the presence 

 of species which may be regarded as the precursors or analogues of recog- 

 nized carboniferous fossils, and in the dominance of generic and sub-gen- 

 eric types which attain their culmination during the carboniferous age. 



1. Species identified Avith fossils from the carboniferous rocks of Amer- 

 ica : 



Producta semireticulata Flem. Coal measures. 



" Cora d' Orb. " " 

 Chonetes lUinoisensis Wor. 



(=C. Logani Hall). Burlington Limestone. 



" multicosta Win. " " 



" mesoloba N&P. Coal measures. 



Hemipronites umbraculum Yon Biich. " " 



Orthis Swallowi Hall, Burlington Limestone. 



Spirifera lineata ? Phil. Coal measures. 



" Grimesi Hall. Burlington Limestone. 



" camerata Morton. Coal measures. 



Nuculana bellistriata Stev. sp. Coal measures. 



Phillipsia Maramecensis ? Shum. Warsaw Limestone. 



2. Species which extend up into the base of the Burlington Limestone 

 at Burlington, Iowa : 



Syringopora Harveyi White. Restricted. 



Trematopora '? vesiculosa Win. " 



" fragilis Win. 



Syringothyris typa Win. Restricted. 



Pentamerus lenticularis W&W.' 

 Aviculopecten Caroli Win. 



Pernopecten limatus Win. Restricted. 



Ctenodonta microdonta Win. 

 Platyceras corniforme Win. 

 Pleurotomaria rota Win. 

 Orthoceras Indianense, Hall. 

 " heterocinctum. Win. 



The species marked "restricted" do not occur below the base of the 

 Burlington Limestone at Burlington, but they are included here because 

 the fauna proper of the Burlington Limestone begins above the narrow 



