520 NORTH AMERICAN INDEX FOSSILS. 





Fig. 699. a, Goniophora ida ; 6, G. truncata ; c, G. hamiltonensis ; d, G. carinata ; 

 e, G. chemungensis. All right valves. (N. Y. Surv,) 



Surface marked by fine undulating concentric striae which are 

 aggregated into folds upon the lower end and anterior portions. 

 Anterior end long. 



Hamilton : New York. 



433. G. chemungensis Hall. (Fig. 699, e.) Devonic. 



Distinguished by its elongate form, short anterior end and fine 

 concentric striae which form folds anteriorly. 



Chemung : New York. 



CXVI. Mytilus Linne. 

 Equivalve, very inequilateral, elongated, usually thin, with 

 terminal pointed beaks. Valves wider and rounded below, gap- 

 ing a little for the byssus, usually smooth. A conspicuous epi- 



