CO^GRYLIA—DITHYRA. 30. 121 



a tubercle near the beaks in each valve, and in one valve a remote 

 one at the end of the groove which receives the ligament. 



30. CRYPTODON- TC/i^TOiV^. 



Testa trigono-globosa, (Bquivalvis, subeequilateralis, clausa. Cardo 

 dente unico obsoleto penetrante cum fovea angustd laterali : laterali- 

 bus nullis, Ligamentum externum. 



Shell triangularly globular, equivalve, nearly equilateral, closed. 

 Hinge with a single obscure penetrating tooth, and a narrow 

 lateral cavity : lateral teeth none. Ligament external. 



This genus in many respects resembles the Lucina, but the pecu- 

 liarity of the hinge necessarily separates it. 



CrYPTODON flexuosus. 



Tab. nost. 7, fig. 9, and 10. 

 Tellina flexuosa. Montagu, Test. Brit. p. 72. 



Pennant, Brit. Zool. iv. p. 183. 

 Linn. Trans, viii. p. 56. 

 Turton, British Fauna, p. 151. 

 Wood, Conch, p. 188, tab. 47, fig. 7, 8, 

 J)illwyn, Descript. Catal. p. 99. 



