The Pan a a. of the Magnesian Series. 105 



Leptseena barabuensis Whitf. 



Metoptotna barabuensis Whitf. 



Metoptoma recurva Whitf. 



Metoptoma simihs Whitf. 



Metoptoma retrorsa Whitf. 



Scxvogyra swezeyi Whitf. 



Scxvogyra elcvata Whitf. 



Scwvogyra obhcjua Whitf 



1 mention also : 



Euomphalus strongi Whitf 



Ophileta (Raphistoma) pnmordialis Wihchl. 



Palaeacma irvingi Whitf. 



Of the above Raphistoma primordiale Winchl. may be 

 again R. minnesotense (Owen) — Oneota to St. Lawrence. 

 One other — Metoptoma barabuensis Whitf I think is repre- 

 sented hy one specimen from the Jordan sandstone at Osce- 

 ola, Wisconsin. It is not improbable that the whole list con- 

 tains really the missing Gasteropoda of the Saint Lawrence 

 formation. If so then this formation is wider from the One- 

 ota than I think it to be. Still this fauna ma}^ belong to an 

 older formation, preceding the Saint Lawrence. 



Regarding the biological side of the question of the rela- 

 tions of these fossils, it must be observed that to associate, 

 for example the species Raphistoma Icisomellum , R. lew- 

 istonense, R. minnesotense, R. oweni is to extend the limits 

 of the genus. These with Ophileta ahurcnsis form an inter- 

 esting series of forms which, however, is best not further 

 enlarged upon here. There ma3' in the future be some inter- 

 esting discoveries, for there occur here and there "fucoids" 

 and other structures like fig. 13, pi. 6, from the Shakopee 

 near Pickett Station, Wisconsin, that show the former ex- 

 istence of still other fossils than those thus far found. 



December 6, 1892. 



