242 ILLINOIS STATE ACADEMY OF SCIENCE 



Eridotrypa sp. (c) 



Hallopora ramosa (d'Or.) (c) 



Hallopora subnodosa (Ulr.) (c) Richmond 

 Monotrypa sp. (a) 

 Nicholsonella sp. (c) 



Pachydictya fenestelliformis (Nich.) (r) W. L. 

 Peronopora decipiens (Rom.) (r) A. E. 

 Rhombotrypa crassimuralis (Ulr.) (r-c) Fernvale 

 Stomatopora arachnoidea (Hall) (c) 

 cf. Glyptocrinus decadactylus Hall (r) 

 Dalmanella testudinaria (Dalman) (c) 

 Hebertella insculpta (Hall) (c) W. 

 Dinorthis proavita Winchell and Schuchert (c) 

 Plectambonites sericeus (Sowerby) (c) W. L. 



Plectorthis whitfieldi (Winchell) near P. kankakensis (McC) (c) 

 Rafinesquina alternata (Conrad) (c) Richmond 

 Rhynchotrema capax (Conrad) (c) Richmond 

 Rhynchotrema neenah (Whitfield) (c) 

 Strophomena neglecta (James) (c) W. 

 Strophomena wisconsinensis Whitfield (r) 

 Modiolopsis concentrica Hall and Whitf. (c) W. 

 Hormotoma sp. 



The species of fossils in the foregoing list indicate the 

 same horizon as that which furnished the fossils from 

 Anx Sable Creek, and that in the vicinity of Oswego, 

 and Wilmington. Three of the species in the list are re- 

 stricted to the Waynesville division of the Eichmond in 

 Indiana, and not one of them is confined to any other 

 member of the Indiana Eichmond. The only species in 

 the list that were not fonnd in the Wilmington, Oswego 

 and Anx Sable Creek localities are Corynotrypa inflata, 

 which ranges throughout the Eichmond, Hallopora ra- 

 mosa, which occurs in the Maysville of Indiana, and 

 Modiolopsis concentrica, which is restricted to the Way- 

 nesville formation in the Ohio-Indiana region. These 

 upper Maquoketa strata are thought to represent Way- 

 nesville time, and to correspond in age with the Fern- 

 vale limestone present at Wilmington, and in the vicinity 

 of Oswego, and northwest of Minooka. 



Another excellent exposure of the upper strata of the 

 Maquoketa is in the north bank of Eock Eiver, one and 

 one-fourth miles east of the railroad station at Sterling, 

 Illinois. The detailed section of the outcrop at this place 

 is given below : 



SECTION OP STRATA EXPOSED IN THE NORTH BANK OP 

 RIVER l^i MILES EAST OF STERLING 



Ft. 

 Silurian limestone 



Limestone, yellow to brown, dolomitic, in layers 4-10 inches 

 thick, with few fossils 28 



