Seminula Dawsoni, Hall. 

 Page 359. 

 Figs. 14, 15. Dorsal and profile vieWs of conjoined valves, x 2. 

 Fig. 16. A view of the brachidium naturally preserved by incrustation and 

 exposed by the removal of a portion of the valve, x 2 . 

 Coal Measures. Windsor, Nova Scotia. 



Clintonella vagabunda, Hall. 

 Page 361 . 

 Fig. 17. A dorsal view of an internal cast, retaining the shell at the umbo of 



the pedicle- valve. 

 Fig. 18. View of another specimen similarly preserved. 



Fig. 19. Profile of the same; showing the normal convexity of the valves and 

 the elevation of the median fold on the brachial valve. 



Fig. 20. Ventral view of the same specimen; showing the depth of the median 



sinus. 

 Fig. 21. The interior of an imperfect pedicle-valve; showing the teeth and 



delthyrium. x 2. 

 Fig. 22. The interior of a pedicle- valve; showing the elevation and curvature 



of the teeth, x 2. 



Fig. 23 An internal cast of a pedicle- valve, showing the muscular area crossed 



by plications of the shell, x 2. 

 Fig. 24. The interior of the umbonal region of conjoined valves, viewed from 



in front; showing the mode of articulation and the bilobed cardinal 



process, x 3. 



Fig. 25. An internal cast of the pedicle-valve; showing the division of the 

 muscular scar into adductor and diductor scars, x 2. 



Fig. 26. The umbonal portion of the brachial valve; showing the bilobed hinge- 

 plate, x 3. 

 Clinton group . Drift of icestern New York . 



Atrypina Clintont, Hall. 

 Page 362. 



Fig. 27. An internal cast of the pedicle-valve; showing the adductor and 



diductor scars . x 2 . 

 Fig. 28. The exterior of a pedicle-valve, x 2. 

 Fig. 29. The interior of an incomplete brachial valve; showing the small 



bilobed hinge-plate and low muscular ridge, x 3. 



Fig. 30. A dorsal view of a specimen; showing the internal cast of the brachial 

 valve and the teeth and rostral cavity of the pedicle- valve, x 2. 

 Clinton group . Drift of western New York . 



391 



