PLATE VI. 



Figs. 1 — 3. — Posidoniella piriformis. Three specimens from the Carboniferous Limestone of 

 Settle. In the Collection of the "Woodwardian Museum, Cambridge. (Page 86.) 



Fig. 3 a. — Posidoniella piriformis. — A view of the anterior edge of Fig. 3. (Page 86.) 

 Fig. 4. — Posidoniella pyriformis. The specimen which Phillips referred to Perna (?) from the 

 Carboniferous Limestone of Bolland. In the Gilbertson Collection of the Natural History Museum, 

 South Kensington. (Page 86.) 



Fig. 5. — Posidoniella piriformis. A larger example from the same locality in the same Collection. 

 Fig. 6. — Posidoniella elongata. A specimen from the Carboniferous Limestone of Bolland. 

 Same Collection. (Page 88.) 



Figs. 7 and 8. — Posidoniella semisulcata. A left and a right valve from the shales below the 

 Millstone Grits, Congleton Edge. My Collection. (Page 92.) 



Figs. 9 — 11. — Posidoniella semisulcata. Three specimens showing the hinge-line and anterior 

 adductor muscle-scar. Same locality. My Collection. (Page 92.) 



Fig. 12. — Posidoniella Isevis. The type sjiecimen of Brown's Catillus Isevis, from the shales 

 below the Millstone Grits of High Green "Wood, Todmorden. Owens College Museum. (Page 94.) 

 Fig. 13. — Posidoniella Isevis. A testiferous example from the roof of the Bullion coal, Colne. 

 Same Collection. (Page 94.) 



Fig. 14. — Posidoniella Isevis. A left valve figured by Mr. George Wild as Posidonomya Gibsoni 

 ('Trans. Manch. Geol. Soc.,' 1892, vol. xxi, p. 400, pi. ii, fig. 8), From the roof of the Bullion Coal, 

 Sholver, near Oldham. Same Collection. (Page 94.) 



Fig. 15. — Posidoniella minor. A left valve, showing overlapping of the periostracum. In the 

 Geological Collection, Owens College. (Page 98.) 



Fig. 16. — Posidoniella Kirkmani. The type of Brown's Catillus Kirkmani from the shales of 

 High Green "Wood, Todmorden. Same Collection. (Page 96.) 



Figs. 17 and 18. — Posidoniella minor. Two specimens on a slab covered with examples from the 

 roof of the Bullion coal, near Trawden. Same Collection. (Page 98.) 



Figs. 19 — 21. — Posidoniella Kirkmani. The originals of Brown's Catillus obliquatus and 

 C. costatus from the black shales of High Green "Wood, Todmorden. Same Collection. (Page 96.) 



Figs. 22, 23. — Posidoniella minor. Originals (?) of some of Brown's species. Same locality and 

 Collection. (Page 98.) 



Fig. 24. — Posidoniella Isevis. A piece of fossil wood with specimens of this species in all stages 

 of growth attached by the byssus. Same Collection. (Page 94.) 



Fig. 25. — Posidoniella subquadrata. A left valve from the roof of the Bullion Mine, Dearnley, 

 Rochdale. My Collection. (Page 101.) 



Fig. 26. — Myalina peralata. A left valve from a quarry on Congleton Edge, Cheshire, below 

 the Millstone Grits. My Collection. (Page 119.) 



