3G4 



HALL AND SARDESON" — PALEOZOIC FORMATION'S OF MINNESOTA. 



The fauna is meager in species, yet remarkably abundant in indi- 

 viduals. It is as follows : 



Pachydictya occidentalism Ulrich. 

 Stictopora mulabilis </), Ulrich. 

 Leptsena minnesotensis, Sardeson 

 Orthis minnesotensis, Sardeson. 

 0. pectinella, Emmons. 

 0. rogata, Sardeson. 

 0. tricenaria, Conrad. 



Pkolidops trentonensis (?), Hall. 

 Rhynchonella increbescens, Hall. 

 Streptorhynchussubsulcatum,Sa,rdeson. 

 Strophomenct alternata, Conrad. 

 Zygospira recurviroslris Hall. 

 Bellerophon bilobatus, Sowerby. 

 Modiolopsis recttformis (?), Worthen. 



The Orthisina Bed. — This bed is of varying thickness. It may be 

 considered, perhaps, the first of the Galena 1 mm Is. It is made up of shaly 

 limestone, shales with calcareous lumps and firm but thin calcareous 

 strata. Fossils are very numerous, both in individuals and species: 

 mollusca are well preserved in the calcareous parts and molluscoidea in 

 the shales. It is well exposed at Kenyon. The name is given from one 

 of its characteristic species. 



The fossils are — 



Receptaculites iowt nsis, Owen. 

 R. vice ni, Hall. 



Pachydictya occidentalism Ulrich. 

 Leptsena minnesotensis, Sardeson. 

 Lingula recinaformis (?), Hall. 

 Or/hi* biforata, Schlotheim. 

 0. minnesotens-is, Sardeson. 

 0. rogata, Sardeson. 

 0. trict mi rin, ( 'onrad. 

 Orthisina americana, Whitfield. 

 Pholidops trentonensis (f), Hall. 

 Rhynchonella increbescens, Hall. 

 R. sancta, Sardeson. 

 Streptorhynchus filitextum, Hall. 

 S. subsulcatum, Sardeson. 

 Strophomena alternata, Conrad. 



Zygospira recurvirostris, Hall. 

 Bellerophon bilobatus, Sowerby. 

 Bucania bidorsata, Hull. 

 B. buelli, Whitfield. 

 B. punctifrons, Emmons. 

 Fusispira elongata, Hall. 

 Holopea perundosa, Sardeson. 

 Murchisonia alexandra, Billings. 

 M. bellicincta, Hall. 

 M. gracilis, Hall. 

 M. in ilb ri. Hall. 



Raphistoma A nticulare, Emmons. 

 Subulites elongatus, Emmons. 

 Trochqnema umbilicatum, Hall. 

 Tellenomya asiartseformis, Salter. 

 Whitella truncata, Ulrich. 



The Camarella Bed. — This member of the series is 30 feet thick. The 

 bed is composed of carbonaceous limestone which quarries very well, yet 

 splits into thin irregular lamina' when exposed to the air. It is quite 

 impregnated with iron pyrites with some chalcopyrite intermingled. It 

 is separated quite sharply from the Orthi.-simt lied aim differs from it in 

 possessing few fossils, as well as in faunal and lithologic characters. Its 

 fossils are — 



