Pl^ATK LXXin— Continued. 



Genus AMPHIGENIA, Hall. 



See Plate 74. 



Ahphiqenia elongata, Vauuxeni. 



Pijf. 16. Ventral view of a cast of the interior of the pedicle-valve ; showing the tilling of the spondylium 

 and the cavity of the short median septum. 



Schoharie grit. Schoharie, New York. 

 Kg. 17. The interior of the umbonal portion of a brachial valve ; showing the structure of the hinge- 

 plate, its apical perforation, and the crura with their jugal processes. 

 Fig. 18. Pi-otile view of the same specimen somewhat enlarged to show the direction and extent of the 



crura, jugal ajxiphyses and crural plates. 

 Fig. 19. The interior of the umbonal portion of the pedicle-valve ; showing the teeth and the entire spon- 

 dyHum. 



Comiferous limestone. Le Roy, New York. 

 Fig. 30. The interior of the umbonal portion of a pedicle-valve ; showing vascular sinuses on the surface 

 of the valve beneath the spondylium. 



Comiferous limentone. From the Mft of Southern Midngan. 



