PLATE XI 



Page. 

 TELUNOMYA T HAMBURGENSIS , 76 



Fig. 1. Left valve, enlarged to two diameters, to show the fine surface strise. 



la. Same valve, showing the posterior margin more depressed, which is the usual form 

 of the species, enlarged to two diameters. 



LlNGULAt MANTICULA 13 



Fig. 2. A specimen of the broad variety of the species, from which the outer surface is 

 exfoliated, enlarged to two diameters. See plate ix, fig. 3. 



ORTHIS PERVETA 72 



Figs. 3, 3 a, 36. Dorsal, ventral, and lateral views of a characteristic specimen, enlarged to 

 two diameters. 



ORTHIS TRICENARIA 74 



Figs. 4, 4 a. Ventral and dorsal views, showing the strong radiating costse and form of the 

 valves, enlarged to two diameters. 



ORTHIS HAMBURGENSIS 73 



Fig. 5. Ventral valve, enlarged to three diameters to show the fissicostato plications and 



general form of the valve. 

 5 a. Same, of the dorsal valve. 



ORTHIS LONENSIS 74 



Fig. 6 Ventral view and outline of the convexity of the ventral valve. Natural size. 

 60. View of the area, showing the triangular-shaped foramen. 



TRIPLESIA CALCIFERA 75 



Fig. 7. Ventral valve, enlarged to two diameters. 



8. Ventral valve of this or an allied species. The valve is convex and the median fold 

 rounded. 



STREPTORHYNCHUS MINOR 75 



Fig. 9. Ventral valve, enlarged to two diameters. 



ORTHIS TESTUDINARIA 72 



Fig. 10. Ventral valve. The cardinal angles are more rounded in the specimen. 

 10 a. Dorsal valve a little enlarged. 



RECEPTACUIITES MAMMILLARIS 65 



Fig. 11. View looking on the base of a small specimen. 



EECEPTACULITES ELLIPTICUS 67 



Fig. 12. Lateral view. 



MODIOLOPSIS POGONIPENSIS 78 



Fig. 13. View of the left valve enlarged to two diameters. See plate i, fig. 6. 



MODIOLOPSIS OCCIDENS 



Fig. 14. Outline of a large right valve, as seen on a weathered surface of rock. 



14 a. Smaller right valve, showing the exterior form. Natural size. See plate i, fig. 5. 



