PLATE 4. 



Page. 



Figs. 1 and 2. Inoceeamus umbonatus 44 



1, a. Au imperfect cast of a right valve, supposed to belong to this species. 



1, U. An anterior profile view of the same. 



2, a. Au anterior view of an internal cast of the left valve, with portions of the external 



fibrous layer seen in the mnboual region. 

 2, h. Another view of a east of a left valve, reduced in size. 



Fig. 3. Venieixa Mortoni 154 



:;, a. A right-side view of type-specimen. 

 3, 6. A posterior dorsal view of same. 



Fig. 4. Venieixa goniophoua 152 



A right-side view of the type-specimen, consisting mainly of a cast of the interior. 



