behind. Shell substance moderately thick. The cast shows 

 a low ridge (depression on the interior of the shell) running 

 obliquely from the umbos toward the posterior extremity. 

 Unfortunately there is not sufficient shell substance pre- 

 served to ascertain whether this depression marked a fold 

 on the exterior of the shell. The small piece of shell still 

 adherent to the cast is moderately thick, and shows the 

 sculpture to have been concentric and regular but not pro- 

 nounced. The anterior adductor impressions are faint, the 

 posterior the most prominent, broad and shallow and 

 situated high in the valve. Pallial line indistinct. Hinge 

 line short and straight, the cast showing the right valve 

 to have had one prominent cardinal tooth, fitting into a 

 corresponding socket in the left valve. 



Dimensions — Length 1 inch ; height f of an inch ; thick- 

 ness of united valves of cast h an inch. 



Loc. Barrier (D). 



Hor. Wandrawandian Series. 



Obs. Only one specimen was found— an internal cast of 

 both valves with some shell still adherent. The large 

 cardinal tooth and thick shell, evidently show this to be 

 co-generic with Astart ila (Paoliudomus) sp. (type A). 

 Astartila sp. (Type C). 



Description— Shell almost circular in form, somewhat 

 inflated, and very slightly elongated behind. Owing to 

 variation in the thickness of the shell, the cast is almost 

 triangular. Umbos not very prominent, and almost cen- 

 trally situated. Ligament external (opisthodetic), but 

 short and narrow. Adductor impressions very faint and 

 almost indistinguishable. Pallial line not visible. Shell 

 somewhat thin, particularly in the centre. Ornamentation 

 concentric, consisting of numerous fine growth wrinkles. 

 On the cast and running obliquely towards the posterior 



