COyiCHYLlA—DITHYRA. 30. 1^1 



obscure, consisting of 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—Tt^U TOiV^. 



Testa trigono-globosa, fsquiioalvis, suhesquilateralis, clausa. 

 Cardo detite nnico obsoleto penetrante cum foved angusid 

 laterali: lateralibus 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 

 pficuliarity of the hinge necessarily separates it. 



Cryptodon. flexuosiu. 



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

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



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

 JLinn. Trans, viii. p. 56. 

 Tiirton, British Fauna, p. 151. 

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

 Dillwyn, Descript. Catal. p. 99. 



