368 T. E. SAVAGE ALEXANDRIAN SERIES IN MISSOURI AND ILLINOIS 



markedly different from that of the overlying limestone, and the numer- 

 ous corals occurring in the second member are absent from the upper bed. 

 The contact of these rocks with the Maquoketa shale below or with Silu- 

 rian limestone above can not be seen at the place where the section was 

 made. However, early Silurian strata thought to represent some part of 

 the Sexton Creek (Brassfield) limestone are exposed a few rods east of 

 this place at a level only a few feet higher than the top of the uppermost 

 member of the section. A blue plastic shale, that doubtless belongs to 

 the Maquoketa, outcrops in the bank of the river about one-half mile 

 farther east at an altitude slightly above that of the top of the section. 

 In the vicinity of Millsdale, where the contact of the lower layers of 

 Silurian limestone with the underlying Maquoketa shale is well exposed, 

 the Channahon limestone is absent. 



The Channahon limestone furnished the fossils listed in the left-hand 

 column below. In the column on the right are given the names of the 

 species from the Edgewood limestone in Missouri and Alexander County, 

 Illinois, that are nearly related to the respective Channahon forms. 



Comparative Table of Fossils 



Fossils from the Cbannahon limestone in 

 Will County, Illinois 



Zaphrentis ambigua Savage 

 Zaphrentis subregularis Savage 

 Zaphrentls stolesi Edwards and 



Haime ? 

 Atrypa ? sp. 



Dalmanella elegantula var. 

 Leptama rhomboidalis (Wilckens) 

 Lingulops illinoisensis Savage 

 Pholidops subelliptica Savage 

 Rhipidomella hybricla (Sowerby) 

 Rhynchotreta lepida Savage 

 Rhynchotreta intermedia Savage 

 Schuchertella curvistriata Savage 

 Whitfieldella acuminata Savage 

 Whitfieldella ovoides Savage 

 Callonema pristina Savage 

 Cycloncma daytonensis Foerste 

 Diaphorostoma illinoisensis Savage 

 Pterinea elegans Savage 

 Datcsonoceras tenuilineatum Savage 

 Cyphaspis intermedia Weller 

 Metapolichas ferrisi Weller 

 Proetus channahoncnsis Weller 

 Leperditia illinoisensis Savage 



Fossils from the Edgewood formation in 



Missouri, and Alexander county, 



Illinois 



Zaphrentis ambigua Savage 

 Zaphrentis subregularis Savage 

 Zaphrentis stokesi Edwards and 



Haime 

 Atrypa putilla (Hall and Clarke) 

 Dalmanella edgeicoodensis Savage 

 Leptcena rhomboidalis (Wilckens) 



Rhynchotreta parva Savage 

 Rhynchotreta thebesenMs Foerste 

 Schuchertella propinqua (M. and W. ) 

 Whitfieldella billingsana (M. and W.) 

 ^Yhitficldclla oroides Savage 



Cycloncma daytonensis Foerste 

 Diaphorostoma niagarensis Hall 

 Pterinea theltesensis M. and W. 



Dawsonoceras cf. ten uilineatum Savage 

 Cyphaspis intermedia Weller 

 Metapolichas breviceps var. clinton- 



ensis Foerste 

 Proetus (letcrminatus Foerste 





