412 



PLATE VI. 



I, 2. Tryblidium validum ; dorsal and lateral views of a cast with the 

 muscle scars emphasized on the latter figure. 



3, 4. Tryblidium exsertum ; lateral and dorsal views of an interior 

 cast. 



5, 6. Carinaropsis deleta ; lateral profile and dorsal view. 



7, 8. Metoptoma explanata ; lateral and dorsal views. 



g. Pleurotomaria clivosa ; outline of a specimen with the direction of 

 the concentric markings indicated. 



lo, II. Fusispira spicula; (lo) the specimens seen on a slab, and 

 (ii) reconstruction of the same. 



12, 13. Holopea perundosa; apical view of a somewhat imperfect cast; 

 transverse section of another specimen indicating the outline of the aper- 

 ture. 



14, 15, 16. Carinaropsis phalera; (14) outline of a cast, (15) longi- 

 tudinal section with the lower part reconstructed from another specimen, 

 and (16) transverse section near the highest elevation of another specimen. 



17. Conchopeltis obtusa ; interior cast in soft limestone. 



18, 19, 20. Tellinomya lepida; (18, 19) interior and exterior of a let: 

 valve, and (20) posterior view. 



21. Cypricardites minnesotensis. 



22. Cypricardites vicinus ; an interior cast reconstructed from another 

 specimen on a slab so as to show the hinge and the outline of the exterior 

 of the original shell. 



23- Cypricardites triangularis ; interior cast. 



24. Tellinomya ( ?) candens ; exterior and interior casts and dorsal 

 view. 



25, 26. Cypricardites luculentus. 



