Unionidce. of the Country of the Iguanodon. 405 



Fig. 2. Right valve cleared. — (Reduced sketch.) 



a. Single cardinal tooth, b. Double cardinal tooth, c. Lamellar tooth, rf. An- 

 terior muscular imprint, e. Posterior muscular imprint, f. Muscular imprint of 

 foot. g}g,g- Palleal imprint. 



Fig. 3. Right valve cleared. — (Reduced sketch.) A variety of the above, or 

 perhaps a sexual difference. This shell is shallower than the above, and may 

 have been a male and the others females. 



The annexed outline of the right valve (fig. 2) will convey 

 an idea of its character. The tooth-plate is very strong and 

 thick ; the cardinal teeth are well developed ; there is a deep 

 fosse or hollow beneath the lateral plate. The anterior muscu- 

 lar imprint is deep, and in front of the cardinal plate ; having the 

 lesser impression, produced by the attachment of the retractor 

 muscles of the foot, on its inner aspect. The posterior imprint 



Vol. xLvii, No, 2.— July-Sept. 1844. 52 



