484 C. R. STAUFFER 



found outside of it in Ontario, and even the fourth but sparingly. 

 It seems certain, therefore, that this is the same horizon in both 

 cases. From the prominence of Bactrites arkonensis in this layer 

 at Arkona and Sandusky, it may be termed the Bactrites horizon. 

 The question next arises as to the relationship of the beds above 

 the Bactrites horizon. In the Sandusky region the fossils of this 

 portion of the formation seem to be more abundant in certain 

 streaks or beds. To a limited extent the same is true of the shales 

 below the Encrinal limestone in Ontario, but there the great body 



Fig. 4. — The Prout or Encrinal limestone overlain by the Huron shale at Slate 

 Cut along the Lake Shore and Michigan Southern Railway three miles east of San- 

 dusky, Ohio. 



of the deposit between the Bactrites layer and the Encrinal lime- 

 stone is very sparingly fossiliferous. The Encrinal limestone may 

 be described as several layers of a hard, pyritiferous, bluish-gray 

 limestone which is often full of crinoid fragments — a description 

 which fits equally well the Prout limestone (Fig. 4) in the sections 

 here under consideration and especially the middle layers at 

 Bloomingville. Along Eighteen Mile Creek, New York, one of the 

 important fossils of the Encrinal limestone is Delthyris sculpt His. 

 Grabau says: "This species is entirely restricted in this region to 

 the Encrinal limestone, and may be regarded as the typical fossil 

 of the fauna." 1 This is also the case in Ontario and probably led 

 Shinier and Grabau to correlate the limestone in Ontario with 



1 Bulletin of the Buffalo Society of Natural Science, Vol. VI (1898), 32. 



