PLATE X. 



Trimerrlla Ohioensis, Meek (page 54). 



Figure 1. Exterior of an unusually perfect and well preserved pedicle valve, 

 from Durham, supposed to be referable to this species. 

 " \a. Interior of the same. 



Pleurotomaeia Halei, Hall. Var. (page 73). 



Figure 2. Lateral view of a specimen from Durham, showing the height of the 

 spire, and position and comparative prominence of the alate slit 

 band. 

 " 2a. Umbilical side of the same. 



