520 GEOLOGY OF OHIO. 



names by means of which it will be possible to designate accurately the 

 types discussed in any future investigation of phylogenetic problems 

 of Middle Silurian life. 



It has sometimes been questioned, whether the Clinton of Ohio be 

 really identical with the Clinton of New York. With our present knowl- 

 edge of paleontological stratigraphy, precise equivalencies will hardly be 

 expected by the modern paleontologist. The lower part of the New 

 York Clinton has still a strong Medina facies. The shales at the top are 

 by many now considered as practically Niagara in type. The lime- 

 stones and siliceous beds between have a fauna which could very profit- 

 ably be made the subject of renewed investigation, but from the glimpse 

 the writer was able to obtain of the same in the cabinet of Dr. B. N. S. 

 Ringueberg, at L-ockport, New York, he is of the opinion that the Clin- 

 ton of Ohio, with its upper shaly courses corresponds as well as could be 

 expected with the siliceous and limestone beds of the upper half of the 

 Clinton in western New York, and to those shaly layers immediately 

 above which are of an acknowledged Niagara type, excepting that in 

 western New York it seems possible to draw a line between the two, and 

 in Ohio this line can not be drawn until the base of the Dayton lime- 

 stone or, in its absence, the base of the dolomitic Niagara shales (or the 

 Waldron shales in Indiana) has been reached. 



The following table includes a list of the fossils common to the 

 Clinton of Ohio and Indiana and that of New York, as far as may be de- 

 termined from the literature available. Some of these forms also occur 

 in the Niagara of New York, so that the comparison is not satisfactory. 

 When the comparative study of the typical Clinton and Niagara faunas 

 of New York is again taken up, there will be provided a more satisfactory 

 basis for the correlation of the Ohio Clinton fauna with the typical fauna 

 of New York. 



Acidaspis Ortoni. 



Illcsnus Daytonensis. 



Calymene Voidest. 



Sphcerexochits pisum. 



Phacops trisulcatus. 



Encrinurus punctatus. 



Comulites distans. 



Orthoceras clavahun. 



O. virgulatum? 



O. (Discosorus) co7ioideum. 



Bellerophon fiscello sttiatus, differs from B. stigmosa only in the absence of a carina 



B. ( Bucania ) trilobatus. 



Platyceras {Platystoma) Niagarense, the small Clinton form. 



Loxonema subulatum. 



Cypricardites Caswelli. 



Plectambonites transversalis, var. elegantuhis. 



Leptcsna rhomboidalis, small Clinton form. 



Strophomena patenta. 



