PLATE nil 



MONOMERELLA OVATA (page 5). 



Figure 1. Specimen with both valves. 

 " lo. Another view of the same. 

 " 16. Interior of a ventral or pedicle valve. 



" Ic. Portion of another ventral valve to show the deltidium and 

 deltidial slopes. 



MoNOMERELLA OVATA, VAR. LATA., (page 6). 



Figure 2. Interior of a ventral valve. 

 " 2a. Natural cast of the interior of a ventral valve. 



Ehtnobolus Galtensis, Billings, Sp. (page 7). 



Figure 3. Interior of a dorsal or brachial valve. 

 " 3a. A ventral or pedicle valve, to show the hinge area. 



BucANiA STTGMOSA (?) Hall, (page 34). 



Figure 4. View of another specimen, to show the somewhat expanded 

 aperture and sinus on the outer lip. 



EccuLiOMPHALus ciRCiNATUs (page 35). 

 Figure 5. Outline of a transverse section of the shell near the aperture. 



