PLATE XIV. 

 Pterinea bsisa, Hall. 



Page 384. 



Fio. 1. View of the left valve of a specimen of this species partly denuded of the shell. The 

 large quadrangular muscular impression is seen near the posterior wing ; the anterior 

 and posterior teeth are also visible. 



Ambonycbia acutirostra, Hall. 



Page 383. 

 Fia. 2. View of the left valve of a full grown individual. 



Ambonychia aph^ea, Hall. 



Page 383. 

 Fig. 3. View of the left valve, showing impressions of the lateral teeth. 



MODIOLOPSIS RECTUS, HaLL. 

 Page 386. 



Fig. 4. The right valve of a small specimen, showing the muscular impressions. 

 " 5. The left valve of a larger individual, showing muscular impressions and teeth. 



Cypricardinia arata, Hall. 



Page 385. 

 Fig. 6. View of the right valve of a specimen of this species, of the natural size. 



MODIOLOPSIS DICT^US, HaLL. 

 Page 385. . 



Fig. 7. View of a cast of the left valve, showing impressions of the lateral teeth. 

 Gypricardites ? quadrilatera. Hall. 



Page 388. 



Fig. 8. A cast of the right valve of the species. 

 " 9. View of the anterior slope, showing the filling of the anterior muscular impression near 



the beak. 

 " 10. The posterior slope of the valve, showing the lateral teeth and impression of the elevated 

 muscular scar. 



Pal^ocardia cordiiformis. Hall. 



Page 389. 



Fig. 11. The right side of the cast, showing the muscular scar. 

 " 12. Posterior profile of the cast. 



Ampsic(elia leidyi. Hall. 



Page 387. 



Fig. 13. Cast of a left valve of a small individual. 

 " 14. Cast of the left valve of a large specimen, in which there are faint traces of muscular 



impressions. 

 " 15. Cast of another individual, having somewhat difierent proportions and a more perfect 

 outline. 



