236 ILLINOIS STATE ACADEMY OF SCIENCE 



water formations, and Cypkotrypa stidhami that occurs 

 in Indiana only in the Whitewater formation, are pres- 

 ent in Illinois in the same layers that contain Hebertella 

 insculpta and other species that in Indiana are restricted 

 to the Waynesville formation. Such species do not in- 

 dicate that the rock from which they come are Liberty 

 or Whitewater in age, but they show that some of th.3 

 species have a different vertical range in Illinois from 

 what they do in Indiana. The range of the species indi- 

 cated in the above list is conclusive evidence that the 

 Fernvale limestone at Wilmington, Illinois, corresponds 

 in age to that of the Waynesville more closely than to 

 any other formation of the Indiana Richmond, and it is 

 considered as Waynesville in age. 



Another exposure of Richmond limestone occurs near 

 the mouth of Rock Run, about six miles west of Joliet, 

 where the section is as follows : 



Feet 



Shale, bluish to yellowish, slightly sandy; few or no fossils 18 



Concealed 4 



Limestone, gray, subcrystalline, in rough layers 4 to 5 inches thick, 

 alternating with bands of bluish-gray, calcareous shale. Fossils 



are numerous in the limestone layers 4 



Limestone, gray, subcrystalline, in uneven layers 3 to 8 inches 

 thick, containing many fossils 7 



The fossils collected from the limestone layers at the 

 Rock Run locality include the following species: 



FOSSILS FROM THE RICHMOND STRATA ON ROCK RUN 



Anaphragma mirabile U. & B. (r) 

 Arthroclema angulare Ulr. (r) 

 Batostoma prosseri C- & G. (r) W. L. 

 Bythopora delicatula (Nich.) (r-c) W. L. Wh. 

 Bythopora meeki (James) (a) W. L. Wh. 

 Coeloclema oweni (?) (James) (r) 

 Dicranopora emacerata (Nich.) (r) Richmond 

 Eridotrypa simulatrix Ulr. (r-c) W 

 Favositella epidermata (Ulr.) (r) Fernvale 

 Helopora imbricata Ulr. (r-c) Fernvale 

 Hemiphragma imperfectum (Ulr.) (r-c) Fernvale 

 Mesotrypa patella (Ulr.) Wh 

 Nicholsonella cumulata (r) Fernvale 

 Nicholsonella punctata (Whir.) 

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

 Pachydictya firma Ulr. (c) Fernvale 

 Pachydictya gigantea Ulr. (a) Fernvale 

 Pachydictya sp. (c) 

 Petigopora sp. (r) 



Rhombotrypa quadrata (Rom.) (a) W. L. Wh. 

 Dinorthis subquadrata (Hall) (c) L. Wh. 



