xvi. CONCHYLlA—DlTHYIiA. 



29. Strigilla. — Testa bifariam anguloao-striatu. 



Shell with angular strife in opposite directions. 



27. Tellina. — Testa antice Jlexuosa, dentibns siibhinis. 



Shell flexuous at the anterior side, with two teeth 

 in one or both valves. 



41. Cardiubi. — Testa cordata umbo/iibus contigiiis, dentibns 



duobus cum lateralibns in utrdqtie valvd. 

 Shell heart-shaped, the beaks close together, with 

 two teeth and two lateral ones in both valves. 



42. IsoCARDIA. — Testa Cordata, umbonibus i-emotis convolutis, 



dentibus duobus cum laterali loiico antico in 



utrdque valvd. 

 Shell heart-shaped, the beaks remote mid convo- 

 lute, with two teeth and a single lateral tooth 

 on the anterior side in each valve. 



c. 



Lio-amodum inter mim . 

 Ligament internal. 



* Cardo edentulus. 

 Hinge without teeth. 



50. Anomia. — Valva inferior basi perforata. 



The under valve perforated at the base. 



