255 



% £ 



Found four feet below the Encrinal limestone, .it Section 

 6 (rare), also in the Strophalosia bed, <>n the Lake Shore. 



Nuculites nyssa. Hall. (Fig. 171.) ( Pal. N. V.. Vol. V.. 

 Pt. L,.p. 328, PI. XLVII.) 



Distinguishing Characters. — Broadly ovate outline, widest 

 at the anterior end; oblique 

 posterior margin, sub-truncate 

 above and rounded below : 



narrow forward-CUr vino' claV- Fig. 171. Nuculites nyssa. Left and 



° right valves, Eighteen Mile Creek (from 



icular ridge. Hall >- 



Found in the Strophalosia bed, on the Lake Shore; "in con- 

 cretionary layers in the shales of the Hamilton group, on the 

 shore of Lake Erie." (Hall, type). 



Nuculites triquetek. Conrad. (Fig. 172.) (Pal. N.Y., 

 Vol. V., Pt, I., p. 326, Pis. XLYIL, XCIII. ) 



Distinguishing Characters. — Short trigonal outline; ob- 

 liquely truncate posterior margin ; arcuate cardinal margin : 



/ 



Fig. 172. Nuculites triqueter. A right valve ; a left valve ; both valves ; the shell is 

 exfoliated, showing impression of clavicle in internal mold (from Hall). 



sub-angular, distinct umbonal ridge; strong, sharply-defined 

 and curved clavicular ridge. 



Found in Transition shales and the upper Marcellus shales, 

 on the Lake Shore (rare). 



Genus SCHIZODUS. King. 



[Ety. : Schizo, split ; odous, tooth.] 

 (1850 : Monograph of the Permian Fossils of England, p. is.!) 

 Shell equivalve, inequilateral, with the posterior side the 

 longest. Anterior outline rounded, posterior tapering. 

 Right valve with two, left valve with three, cardinal teeth. 

 Central tooth of left valve more or less bifid. Pallial line 

 entire. Surface smooth or ornamented with fine raised con- 

 centric lines. 



