PLATE V. 



Fig. 1. — Carbonicola acuta (form a), showing the opposing hinge-plates of oppo- 

 site valves from the Bowling Alley roof, Ivy House Colliery, Bucknall. This I 

 regard as the normal form. My Collection. (Page 51.) 



Fig. 2. — Carbonicola aquilina, showing the opposite hinge-plates of opposite 

 valves. From the same locality as above. My Collection. (Page 69.) 



Fig. 3. — Carbonicola acuta (form a). Left valve, showing hinge. Cockshead 

 Rock, Hulnie Colliery. My Collection. (Page 51.) 



Figs. 5 — 11, 13, 15, 16. — Carbonicola acuta (form a). A series of valves 

 from the Cockshead Rock, Hulme Colliery, Adderley Green, showing minute 

 variations in details in the hinge. My Collection. (Page 51.) 



Figs. 4 and 12. Carbonicola acuta (form o), showing the hinge, from the Ten- 

 foot Coal, Bucknall. My Collection. (Page 51.) 



Fig 14. — Carbonicola acuta (form a). View in profile of a section of the valve 

 through the umbones. Same locality. My Collection. (Page 51.) 



Figs. 17 — 34. — Carbonicola acuta (form /3). A series showing the bevelling 

 of the lower edge of the hinge-plate with occasional facets, and a transverse pro- 

 longation of the cardinal tooth, all with the exception of Fig. 32 from the same 

 locality, this one coming from Hanley ; and Fig. 22, which is from the roof of the 

 Ten-foot, Bucknall. My Collection. (Page 52.) 



Figs. 35 — 37. — Carbonicola acuta. A series showing the elongated cardinal 

 tooth becoming bifid in the right valve. Same locality. Type y. My Collection. 

 (Page 52.) 



Fig. 38. — Carbonicola ovalis. Left valve, showing a central cardinal tooth, 

 with a pit anterior and posterior to it for the reception of the bifid teeth of the 

 right valve. There is a faint indication of a posterior lateral tooth, also some 

 pearly nodules. Same locality. My Collection. (Page 56.) 



Fig. 39. — Carbonicola acuta. Right valve, showing a trifid cardinal tooth. 

 Same locality. My Collection. (Page 50.) 



