58 GENUS VI. TELLINA. 



CoRBULA. Shell ineqviivalve, subtransverse, free, and regular, 

 with a conic tooth recurved on each valve; the carti- 

 lage internal, two muscular impressions (see Brander. 

 Foss. Hant. no. 103; Chemn. vol. 10. f. 1668 and 

 1671). 



Trigonellites. a slightly rounded trigonal thick shell, 

 gaping on each side ; the anterior margin nearly straight, 

 the posterior gently waving. The hinge linear, without 

 teeth ; cartilage external, no appearance of muscular 

 attachment (see Park. Organ. Rem. vol. 3. p. 184. t. 13. 

 /. 10 and 11). 



