PLATE I. 



Fig. 1. A slab of rock from the Cretaceous Plysch, with a. Algites 

 furcatus (p. 255), and 6. Ci^onUrtttiS tntricatug (p. 252). 

 Nat. size. 



Fig. 2. Cf)onHrite£i patuIuU. Nat. size. (p. 253) 



