98 ILLINOIS ACADEMY OF SCIENCE. 



Niagara strata, carrying the common fossils of that horizon, are 

 well exposed a few rods east of this point, at a level only four 

 or five feet higher than the top of the uppermost member of the 

 section. A blue plastic shale, that doubtless represents the 

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

 mile further east, at an altitude slightly above that of the top of 

 the section. At two points in the vicinity of Millsdale, where the 

 contact of the lower beds of the Niagara limestone with the 

 underlying Maquoketa shale is well exposed, the Channahon 

 limestone is absent, and there are present no intervening strata 

 of any kind. 



The limestone members of the foregoing section furnished the 

 following very interesting assemblage of fossils : 



Fossils from the Channahon Limestone. 

 ^Zaphrentis channahoncnsis, n. sp. 

 Zaphrentis stokesi Edwards and Haime? 

 Atrypa piitilla (Hall and Clarke)? 

 Dalmanella elegantula var. 

 Homoeospira channahonensis n. sp. 

 Gypidula cf. simplex Foerste. 

 Leptaena rhomboidalis (Wilckens). 

 Leptobolus illinoiscnsis n. sp. 

 Pholidops channahonensis n. sp. 

 Rhipidomella hybrida (Sowerby). 

 Rhynchotreta intermedia n. sp. 

 Schnchertella curvistriata n. sp. 

 WhitHeldella acuminata n. sp. 

 IVhitfieldella ovoides n. sp. 

 Holopea illinoisensis n. sp. 

 Pterinea elegans n. sp. 

 Dawsonoceras tcnnilineatiim n. sp. 

 Cyphaspis intermedia Weller. 

 Metapolichas ferrisi Weller. 

 Proetus channahonensis Weller. 



Correlation : In the foregoing list of fossils, the species 

 Dalmanella elegantula var., Gypidula cf. simplex and Rhipidomella 

 hybrida indicate a Silurian age, but the fauna as a whole cannot 

 be directly correlated with that of any known Silurian horizon. 

 The greater number of the species have been found at no other 

 place. Out of twenty species in the list, only two species of corals 

 and four of the brachiopods have been described from other 

 localities. The remaining fourteen species are known only from 

 the strata under consideration at this place, and so are of no 

 help in the correlation of the bed. Of the old species, the corals 

 are not definite markers of any Silurian horizon. Of the brachio- 



2. Note; The species of fossils in this paper designated as new, have 

 been described by the writer in a paper that will soon be published in the 

 Bulletin of the Geological Society of America. 



