xviii. CONCHYLIA— Z>/J'^yi2^ 



22. LUTRARIA. — Cadro dente cochleariformi, aim dente trigono 

 adjecto. 

 Hinge with a spoon-shaped tooth, and an addi- 

 tional triangular one. 



20. MoNTACUTA. — Testa (equivalvis, dentibns dicobus cum fovea 

 interpositd. 

 Shell equivalve, with two teeth in each valve and 

 a cavity between thein. 



18. Ervilia. — Testa aquivalvis, dente unico inter duos obsoletos 

 penetrante. 

 Shell equivalve, with a single tooth closing 

 between two obscure ones. 



12. Pandora.— FaZi;a altera dente longitudinali etfoveold, altera 

 foveolis duubus lotigitudinalibus. 

 In one valve a longitudinal tooth and cavity, in 

 the other two longitudinal cavities. 



11. Corbula. — Valva altera dente conico, altera dente cochle- 

 arijormi. 

 In one valve a conic tooth, and a spoon-shaped 

 tooth in the other. 



51. TEREBRATULA. — Valva svperior umbone producto apice 

 perforata. 

 The upper valve with the beak elongated and 

 perforated at the extremity. 



Cardo dentibus primariis et lateralibus. 

 Hinge with both primary and lateral teeth. 



