PLATE I. 



Fig. 



1. Estheria memhranacea (p. 14). — A group on sandy flagstone, nat. size. Caithness. 



2. „ „ A pair of valves, open, and somewhat displaced ; their dorsal edges 



approximate ; the ridges lost in wrinkles : X 4 diam. Caithness. 



3. „ „ A single valve (right) : X 4 diam. Caithness. 



4. „ „ Outline of the same valve, X 6 diam., for comparison with other 



Estherice magnified 6 times. Caithness. 



5. „ „ The surface between two ridges, x 100 diam. Probably showing the 



efiiects of sand-grains interfering with the natural ornament. 

 Caithness. 



6. „ „ Left valve, well preserved, from Kokenhusen, Livonia : x 6 diam. 



7. „ ,, Ornament of an interspace of the same: x 100 diam. 



8. Estheria striata, var. Binneyana (p. 28). — From near Chesterfield, Derbyshire; outline of valve: 



X 6 diam. 



9. „ ,, „ A pair of displaced valves ; nat. size. Near Chesterfield. 



10. „ „ „ Portion of the surface : x 50 diam. Chesterfield. 



11. Estheria striata, var. Beinertiana (p. 25). — Right valve from Shaly Brow, Lancashire: x 6 diam. 



12. „ „ „ Portion of the surface of the same, showing the nearly 



smooth outside, and the wrinkled interior : x 50 diam. 



13. „ ,, „ Left valve; from Silesia ; x 6 diam. 



14. „ „ „ Portion of the surface of the same : X 50 diam. 



15. Estheria striata, var. Tateana (p. 26). — Right valve; Laramerton, Berwickshire : x 6 diam. 



16. 17- ,, „ Cellular structure, remaining in the shale; Lammerton : 



X 75 diam. 



18. „ „ „ Left valve of a shorter individual ; Lammerton: x 6 diam. 



[A still shorter form is shown in the woodcut at p. 26.] 



19. Leaia Leidt/i, \&r. W^illiamsoniana {p. 117). — The inside view of two conjoined valves; Ardwick, 



Manchester: X 6 diam. 



20. „ ' „ „ Right valve, outside ; Ardwick : X 6 diam. 



21. Leaia Leidyi, var. Salteriana (p. 119). — Outline of left valve; Fifeshire: X 6 diam. 



22. Estheria exiffua (p. 27). — Right valve. (Probably young.) Kargala, Russia : X 6 diam. 



23. „ „ The same valve : X 20 diam. 



24. „ „ Portion of the surface : X 100 diam. 



25. Estheria PortlocMi {p. 40). — Hollow mould of right valve ; Rhone Hill, Tyrone : x 6 diam. 



26. Estheria tenella (p. 31). — Right valve; Oschatz, Saxony: X 6 diam. 



27. „ „ Portion of the surface of the same : x 75 diam. 



28. Estheria minuta (jp. 42). — Right valve, its ridges lost in wrinkles ; Sinsheims x 6 diam. 



29. „ „ Left valve of a larger and better preserved specimen ; Sinsheim : X 6 diam. 



30. „ „ Portion of the surface of another specimen, showing the reticulated inter- 



space between the ridges : x 75 diam. 



31. 32. Inoceramus {Posidonomya) Suessii, Oppel (p. 12).— ^From the bluish shale of the Lower Oolite 



(zone of Ammonites torulosus), Kandern, 

 Baden ; for comparison with Estheria 

 minuta. Fig. 31, portion of a valve, and 

 mould of a part of another : x 6 diam. 

 Fig. 32, portion of the surface: X 75 

 diam. (This shell occurs also in the 

 Oxford Clay near Peterborough.) 



