PLATE IV. 





Figs. 1 — 7. — Garbonicola acuta, var. rhomboidalis. Showing the passage from 

 a truncate and obtuse posterior end to a beaked and sinuated form. From the 

 roof of the Cockshead Seam, Adderley Green, North Staffordshire. My Collection. 

 (Page 55.) 



Figs. 8 — 12. — Garbonicola acuta. To show the eroded umbones. Figs. 8 

 and 9 are different views of the same specimen. From the roof of the Cocks- 

 head Seam, Adderley Green, North Staffordshire. My Collection. (Page 50.) 



Figs. 13 — 15. — Garbonicola acuta. A smaller form from the Nether Pit, 

 Derbyshire. My Collection. (Page 50.) 



Fig. 16. — Garbonicola acuta. A form with an almost obsolete anterior end, 

 ? from the Upper Coal-measures of Ayrshire. In the Collection of Mr. Smith of 

 Kilwinning. (Page 50.) 



Fig. 1 7. — Garbonicola acuta. A compressed example from the Coal-measures 

 of Coalbrookdale. In the Collection of Professor Prestwich. (Page 50.) 



Fig. 18. — Garbonicola ovalis. The original specimen figured by Sowerby in 

 Prestwich's "Geology of Coalbrookdale," 'Trans. Geol. Soc.,' Ser. 2, vol. v, 

 pi. xxxix, fig. 13. From the Pennystone beds ? Coalbrookdale. In the 

 Collection of Professor Prestwich. (Page 56.) 



Fig. 19. — Garbonicola ovalis. A cast of both valves from the Coal-measures of 

 Coalbrookdale. In the Geological Collection of the Nottingham Museum. 

 (Page 56.) 



Fig. 20. — Garbonicola ovalis. From the Upper Coal-measures of Lanarkshire. 

 From the Collection of Mr. J. Nielson, of Glasgow. (Page 56.) 



Fig. 21. — Garbonicola ovalis. From the same locality and Collection. A form 

 connecting G. acuta with G. ovalis. (Page 56.) 



Fig. 22. — Garbonicola ovalis. From Butterley, Leicestershire. In the 

 Geological Collection of the Nottingham Museum. (Page 56.) 





