PLATE XX. 



Fig. 1. — Pseudamusium Reilesdalen.se. A left valve with the shell preserved, 

 showing radiating colour bands. Redesdale Ironstone. My Collection. (Page 109.) 

 Fig. 2. — Pseudamusium Redesdalense. A left valve, incomplete at the posterior 

 margin. Same locality and Collection. (Page 109.) 



Figs. 3, 4. — Pseudamusium Redesdalense. The left and right valve 3 ol fcb.3 

 same shell, showing the difference between the two. Same locality and Collection. 

 (Page 109.) 



Fig. 5. — Pseudamusium Redesdalense. — A right valve. Sams locality and Col- 

 lection. (Page 109.) 



Fig. 6. — Pseudamusium Redesdalense. A cast of the interior, showing the 

 adductor scar of the right valve. SaniB locality and CDllection. (Page 109.) 



Fig. 7. — Pseudamusium concentnco-lincntum. The left valve. From Castleton. 

 In the Manchester Museum, Owens College. (Page 111.) 



Fig. 8. — Pseudamusium concentrico-lineatum. A left valve. From Castleton. 

 My Collection. (Page 111.) 



Fig. 9. — Pseudamusium concent rico-lineat urn. A left valve. From the Carboni- 

 ferous Limestone of AVetton, N. Staffordshire. My Collection. (Page 111.) 



Fig. 10. — Pseudamusium concentrico-lineatum. A cast of the left valve. From 

 Askeaton, co. Limerick. In the Collection of the Geological Survey of Ireland. 

 (Page 111.) 



Figs. 11, 12. — Pseudamusium ettipticum. The left and right valves of the 

 same shell, showing the obscure radiating lines on the left and the smooth right 

 valve. From Castleton. My Collection. (Page 103.) 



Fig. 13. — Pseudamusium ettipticum. The left valve. Used and figured as the 

 type by Phillips. In the Gilbertson Collection, Natural History Museum, South 

 Kensington. A little incomplete in front. (Page 103.) 



Fig. 14. — Pseudamusium ettipticum. Not the type of Pecten elongatus, M'Coy. 

 A left valve. From Millicent, co. Kildare. In the Griffith Collection, Museum of 

 Science and Art, Dublin. A compressed and flattened form. (Page 103.) 



Fig. 15. — Pseudamusium ellijpticum. A left valve. From Castleton. My 

 Collection. (Page 103.) 



Fig. 1G. — Pseudamusium ettipticum. A left valve. From Craigenglen. In the 

 Collection of the Geological Survey of Scotland. (Page 103.) 



Fig. 17. — Pseudamusium ettipticum. A left valve. Same locality and Collec- 

 tion. (Page 103.) 



Fig. 18. — Pseudamusium ettipticum. A right valve, more gibbose than usual. 

 From Thorpe Cloud. My Collection. (Page 103.) 



