(10) 



8. TellinA. Lin. M. 



.Orbicular, generally 1 or 2 cardinal teeth Ligament exterior, on 



flattish, anterior side angu- on the same valve : 2 the shortest side. (1) 



lar, presenting an undulat- lateral teeth, 

 ing irregular fold. Fig. 5l. 



at. Shell transversely oblong. 



/?. . . orbicular or a rounded oval. 



9. Tellinoides. Lam. M. 



Inequilateral, flattish, 2 diverging cardinal 



slightly gaping at the sides, teeth on each valve: 2 



beaks small, not swelled, lateral teeth, almost ef- 



without fold. Fig. 36. faced on one valve, 1 of 



them very near the car- 

 dinals. 



Ligament exterior. 



10. Donax. Lin. L. M. 



Equivalved, inequila- 2 cardinal teeth, ei- Ligament exterior, 



teral, anterior side very ther on each valve or on sbort. (2) 



short, and very obtuse, one only, 1 or 2 lateral 



Fig. 27. teeth. 



«. Internal edge of the valves entire. 



distinctly crenated or dentated. 



11. Cytherea. Lam. M. 



Equivalved, inequila- 

 teral, sub-orbicular, tri- 

 gonal. Fig. 28. 



4 cardinal teeth on 

 the right valve (4), 3 of 

 which are diverging, 

 but near together at 

 the base ; and 1 (isola- 

 ted under the 3 diver- 

 ging cardinal teeth) on 

 the other valve, which 

 has a hollow parallel to 

 the edge : no lateral 

 teeth. 



Ligament exterior. (3) 



a. Internal edge of valves entire. 



b. Internal edge of valves crenated or den- 

 tated. 



(Anterior cardinal tooth with a 

 striated channel or a dentated 

 edge. 

 Anterior cardinal tooth neither 

 channelled nor dentated. 



(1) Austral Ocean. They are frequently found at a small depth in the sand on 

 the sea-shore. Foss. in Crag Marl ; at Grignon, Parries, Dax, Bourdeaux, Environs 

 of Troyes. 



(2) These are also found in the sands of the sea-shore. Foss. at Parncs, Beynes, 

 Houdan, Grignon. 



(3) Foss. at Bourdcaux, Mont-Mar ius, Turin, Beauvais, Grignon, Courtagnon, 

 Houdan, Pontchartrain. 



(4) The valve on the right hand, when you hold the shell with its hinges down- 

 wards, and the side with the ligament farthest from you. 



