EXPLANATION OF PLATE XL. 



Diapliragmella merisniopteroides, Eth. fil. 



Fig. 1. Cast of left valve displaying impiessiou of the oblique 

 clavicle, anterior adductor, and external radii. — 

 X 2 diam. 



Fig. 2. Umboual region and imperfect cardinal margin, with 

 impression of the clavicle and teeth — x 2^ diam. 



Modiomorpha mytiliformis, Eth. fil. 



Fig. 3. Internal cast of incomplete left valve. — x 1|^ diam. 



Glyptodesma (F) bundauoonensis, Eth. fil. 



Fig. -4. Internal cast of incomplete left valve, .sliowing the 

 insigniticjint anterior end, high prominent um- 

 bonal region, expanded posterior end, and 

 ligamental furrows, etc. 



Fig. 5. A similar specimen, with traces of the large adductor 

 scar. 



Paracyclas (?) obliqua, Eth. fil. 



Fig. 6. Internal cast of a left valve, displaying the groove 

 left along the posterior cardinal margin for the 

 support of the internal ligament. — x 2 diam. 



Fig. 7. A similar right valve. — x 2 diam. 



[Allorisma] passaloides, Eth. fil. 



Fig. 8. Internal cast of a right valve, faintl}- displaying 

 position of the posterior adductor, and the exter- 

 nal concentric laminae. — x ^ diam. 



