PLATE V. 



Fig. 1. — Myalina Bedesdalensis. A crushed specimen showing the curvature 

 of the posterior border, from Swaledale. In the Collection of Miss Jane Donald. 

 (Page 109.) 



Figs. 2 and 3. — Myalina compressa. Two specimens from the Coal-measures, 

 South Staffordshire. In the Collection of Mr. Johnson of Dudley. (Page 123.) 



Figs. 4 and 5. — Myalina sublamellosa. Two impressions on a slab of cal- 

 careous Sandstone from Swaledale. In the Collection of Miss Jane Donald. 

 (Page 121.) 



Figs. 6, 7, 8. — Myalina sublamellosa. — From the locality where the type- 

 specimens were obtained, Craiglockhart Hill Quarry, near Edinburgh. Calci- 

 ferous Sandstone series. In the Collection of the Geological Survey of Scotland. 

 (Page 121.) 



Fig. 9. — Posidoniella vetusta. A right valve, of medium size, from the 

 Carboniferous Limestone (upper beds) of Cavedale, Castleton. My Collection. 

 (Page 84.) 



Figs. 10, 10 a, 11, 11 ft. — Posidoniella vetusta. Two left valves seen from the 

 side and in profile from behind. Same locality and Collection. (Page 84.) 



Fig. 12. — Posidoniella gibbosa. A specimen showing both valves from the 

 Carboniferous Limestone of Thorpe Cloud. My Collection. (Page 91.) 



Figs. 13 and 14. — Posidoniella gibbosa. Two left valves from the same 

 locality. My Collection. (Page 91.) 



Fig. 15. — Posidoniella elongata. A left valve from the Carboniferous Lime- 

 stone, Axton, Flintshire. In the Collection of Mr. G. H. Morton. (Page 88.) 



Fig. 16. — Posidoniella elongata. A left testiferous example from the Carboni- 

 ferous Limestone of Settle. In the Collection of the Woodwardian Museum, 

 Cambridge. (Page 88.) 



Fig. 17. — Posidoniella elongata. A fairly perfect example from the Coombes 

 Limestone. Collected by Mr. John Dunn. My Collection. (Page 88.) 



Figs. 18, 18 ft. — Posidoniella elongata. The cast of a left valve showing the 

 position of the anterior adductor scar. From the Carboniferous Limestone of 

 Settle. In the Collection of the Woodwardian Museum, Cambridge. (Page 88.) 



Figs. 19, 19 ft. — Posidoniella elongata. — Two views of a fairly perfect example, 

 the second figure being the view of the anterior surface. Same locality and 

 Museum. (Page 88.) 



Fig. 20. — Posidoniella pyriformis. A left testiferous valve of full size from 

 the same locality and Museum. (Page 86.) 



Fig. 21. — Posidoniella pyriformis. The cast of a right valve showing the 

 pallial line and posterior adductor muscle-scar. Same locality and Museum. 

 (Page 86.) 



Fig. 22. — Posidoniella pyriformis. A left valve. Same locality and Collec- 

 tion. (Page 86.) 



