115 



with longitudinal ribs, armed with vaulted scales, im- 

 brications like a rasp, or with striae; the margins cre- 

 nulated, and closely interlocking when the valves are 

 closed: hinge without teeth, and the cardinal cavity 

 receiving the ligament. 



Lima inflata Lima annulata 



squamosa fragilis 



glacialis linguatula. 



[Five fossil species] 



PLAGIOSTOMA. 



Sowerbys Conchology, No. 14, pi. 77 



No recent example of this genus has yet been disco- 

 vered. Lamarck apparently has assigned it this station, 

 to connect together, as an intermediate link, the gene- 

 ra Lima, Pecten, Spondylus, and Podopsis. Shell sub- 

 equivalve, free, subauriculated, cardinal base straight 

 and transverse. Apices a little distant, the external 

 edges of the hinge angular, straight on one side, oblique 

 on the other: hinge without teeth, a cardinal cavity 

 beneath the apices, partly internal, opening outwards, 

 and receiving the ligament. 



[Ten fossil species] 

 i2 



