Handbook of Paleontology 397 



term and the name Genesee (in the restricted sense) 

 was applied to the lower shales, the Genesee black shale, 

 the upper shales receiving the name of West River shale. 

 The name Genesee is used here, as originally, for the 

 black shale only. All of the Senecan above belongs to 

 the Portage (Ulrich). The Genesee black shale com- 

 prises the shales between the Tully and Genundewa lime- 

 stone which extend as far east as the Chenango valley 

 (central New York). They are densely black, bitumi- 

 nous layers with thin bands of gray shales appearing near 

 the top. Pyrites in small nodules is common, and there 

 sometimes occur a few thin flags of finer-grained cal- 

 careous sandstone. These shales have a thickness vary- 

 ing from a few feet to about 100 feet. . The fauna is 

 sparse and the fossils not well preserved. In the west- 

 ward extension the rocks carry a number of species of 

 pelecypods, brachiopods and cephalopods ; but in the 

 more eastern part the formation is quite barren and the 

 above-mentioned forms are for the most part absent. 

 Plant remains are not uncommon in the black shales and 

 conodonts and fish plates occur. Among the fossils are 

 the brachiopods Orbiculoidea lodensis, Lingula spatula 

 and the main guide fossil Schizobolus truncatus; the 

 pelecypods Pterochaenia fragilis, Liorhynchus quadri- 

 costatus; the gastropod Euryzone (Pleuroiomaria) rugu- 

 lata; the pteropod Styliolina fissurella; the cephalopods 

 Probeloceras lutheri and Bactrites aciculum. 



The Portage beds (Hal! '40) received their name 

 from Portageville on the Genesee river and now include 

 the formations between the Genesee and the Chemung 

 beds (Hall '43), though originally only the formations 

 above the Gardeau were included in this term (figure 53). 

 Tn western New York these formations are characterized 



