BY CHARLES HEDLEY. 



431 



marks the position of the resilium. The tract which I suppose 

 to be occupied by the ligament is obscurely perpendicularly 



grooved, and may correspond 

 to the crenulated provinculum 

 figured by Bernard in the young 

 stage of Leda fi'agilis* Hinge 

 line arched, broad and strong, its 

 central tliird occupied by the 

 ligament ; on the posterior side 

 are three stout, projecting pyra- 

 midal teeth arising from V- 

 shaped roots of which one leg is 

 much longer than the other; on 

 Fig. 1. the antei'ior side two such are 



followed by small tubercles. Beyond the teeth the margin is 

 on either side crenulated for some distance. 



Within (fig. 1, interior of left valve) the surface though not 

 nacreous is most glossy, the external sculpture visible through 

 the shell. The oblique external folds show as deep furrows which 

 undulate the margin and traverse the valve. Pallial line simple; 

 the adductor muscle scars are very distinct, so that if a pallial 

 sinus existed it would be readily dis- 

 cernible. Ventral margin smooth and 

 straight. 



Externally (fig. 2, right valve of 

 another specimen) the lunule and escut- 

 cheon are feebly marked. From the 

 umbo three sharp ridges and intervening 

 furrows cross the valve to the postero- 

 ventral margin. Posterior uf these folds 

 the valve is somewhat truncated and 

 flattened, its surface is divided into three 

 facets by minor radiating ridges ; anteriorlj^ it is smooth and 

 rounded. The entire external surface is glossy and ornamented 



Fig. 2. 



* F. Bernard, Bull. Soc. (i€o\. France, (3) xxiv. 1896, p. 79, fig. 12. 



