28 NEW YORK STATE MUSEUM 



The following fossils have been found in this gray band in ex- 

 posures in the Seneca lake and Cayuga lake valleys : 



Manticoceras pattersoni (Hall) Atrypa reticularis (Linne) 



Gomphoceras cf. manes Hall Ambocoelia unbonata (Conrad) 



Bactrites sp. Chonetes scitulus Hall 



Paleotrochus praecursor Clarke Liorhynchus multicostatum (Hall) 



Pleurotomaria capillaria Hall Orbiculoidea lodensis Vanuxem 



Loxonema noe Clarke Lingula spatulata Vanuxem 



Styliolina fissurella (Hall) Cladochonus, abundant in concre- 



Buchiola retrostriata (von Buck) tions 



Palaeoneilo muta Hall Crinoid stems 

 Pterocbaenia fragilis (Hall) 



West River dark shale 



In Ontario county and westward to Lake Erie the dark shales 

 between the Genundewa limestone and the base of the Cashaqua 

 shales are separable into two divisions : the West River shale, a 

 heavy bed of soft dark colored slightly calcareous shales, and suc- 

 ceeding them, the blacker and more bituminous Middlesex shale. 



In the Seneca lake valley the distinction between the two forma- 

 tions is scarcely recognizable and in the Cayuga lake valley it seems 

 to be lost entirely and both formations by gradual change in the 

 character of the sedimentation become so far assimilated to the suc- 

 ceeding Cashaqua shale that they are not to be distinguished from 

 that formation east of this, or at farthest, the Moravia quadrangle. 

 The horizon of the West River and Middlesex shales is exposed in the 

 upper part of the Sheldrake and other ravines in that vicinity, also 

 in the Trumansburg and Taghanic ravines and others in the vicinity 

 of Heddens and King Ferry. In the Salmon creek valley these beds 

 may be seen at the top of the falls in the ravine 2^ miles north of 

 Ludlowville, and in several gullies on the east side between Genoa 

 and Venice Center. 



Fossils are very rare in these beds but a few forms like those in 

 the Genesee beds occur. Among these are : 



Bactrites aciculum (Hall) Panenka sp. 



Gephyroceras sp. Lingula spatulata Vanuxem 



Pterocbaenia fragilis (Hall) Orbiculoidea lodensis Vanuxem 



Lunulicardium curtum Hall Liorhyncbus quadricostatum Hall 

 Buchiola retrostriata (von Buck) 



