ORDOVICIAN AND SILURIAN BRACHIOPODA OF THE GIRVAN DISTRICT. 989 



Fig. 39. Ditto. Internal cast of pedicle-valve. x 2. Same horizon and locality. G. 

 Fig. 40 Ditto. Interior of brachial valve. x 2. Same horizon and locality. G. 

 Fig. 40a. Ditto. Posterior view of same specimen. x 2. 



Fig. 41. Plectambonites transversalis (Dalm.), var. nov. mullochensis. Internal cast of pedicle-valve, 

 x 2. Mulloch Hill Group, Mulloch Hill. G. 



Fig. 41a. Ditto. Posterior view of same specimen. x 2. 



Fig. 42. Ditto. Internal cast of brachial valve. x 2. Same horizon and locality. G. 



Plate XVI. 



Fig. 1. Plectambonites transversalis (Dalm.), var. nov. mullochensis. Impression of exterior of brachial 

 x 2. Mulloch Hill Group, Mulloch Hill. G. 



Fig. 2. Ditto. Pedicle-valve (shell partly abraded). x2|. Same horizon and locality. G. 



Fig. 3. Plectambonites transversalis (Dalm.), var. nov. penkillensis. Pedicle-valve. x 2. Camregan 

 Group, Bargany Pond Burn. G. 



Fig. 4. Ditto. Impression of exterior of brachial valve. x 3. Same horizon and locality. G. 



Fig. 5. Ditto. Internal cast of pedicle-valve. x 2. Same horizon and locality. G. 



Fig. 6. Ditto. Pedicle-valve. x 2. Penkill Group, Penkill. G. 



Fig. 7. Ditto, ditto (shell partly abraded). x 2^. Same horizon and locality. G. 



Fig. 8. Plectambonites transversalis (Dalm.), var. nov. tricostata. Pedicle-valve. x 3. Saugh Hill 

 Group, Woodland Point. G. 



Fig. 9. Ditto, ditto. x 4. Same horizon and locality. G. 



Fig. 10. Ditto. Brachial valve. x 3. Same horizon and locality. G. 



Fig. 11. Ditto. Pedicle-valve. x 4. Same horizon and locality. G. 



Fig. 12. Ditto, ditto. x 3. Same horizon and locality. G. 



Fig. 13. Ditto, ditto. x 3. Same horizon and locality. G. 



Fig. 14. Plectambonites!: youngiana (Dav.). Interior of brachial valve. x 1J. Stinchar Limestone 

 Group, Craighead. G. (Figured, Davidson, Suppl., pi. xii, fig. 16.) 



Fig. 14a. Ditto. Side-view of same specimen. x 1J. 



Fig. 15. Ditto. Interior of brachial valve. x \\. Same horizon and locality. G. 



Fig. 16. Ditto. Complete shell, brachial side. x \\. Same horizon and locality. G. (Figured, 

 Davidson, Suppl., pi. xii, fig. 15.) 



Fig. 17. Ditto. Pedicle-valve. x \\. Same horizon and locality. G. 



Fig. 18. Ditto. Internal cast of pedicle-valve. x 1|. Same horizon and locality. G. 



Fig. 19. Stropheodonta arenacea (Salt.). Interior of brachial valve (from squeeze). x 1£. Camregan 

 Group, Camregan Wood. G. 



Fig. 20. Stropheodonta corrugatella (Dav.). Internal cast of imperfect brachial valve. x 1|. Starfish 

 Bed, Drummuck Group, Thraive Glen. G. 



Fig. 21. Stropheodonta donax, sp. nov. Internal cust of pedicle-valve. x \\. Starfish Bed, Drum- 

 muck Group, Thraive Glen. G. 



Fig. 22. Ditto. Impression of exterior of same shell. x 1^. G. 



Fig. 23. Ditto. Internal cast of pedicle-valve. x 1-|. Same horizon and locality. G. 



Fig. 23a. Ditto. Cardinal region of same specimen. x 2£. 



Fig. 24. Ditto. Pedicle-valve (from squeeze of external impression). x 1|. Same horizon and 

 locality. G. 



Fig. 25. Ditto. Cardinal region of pedicle-valve. x 2£. Same horizon and locality. G. 



Fig. 26. Ditto. Brachial valve. x 1£. Same horizon and locality. G. 



Fig. 27. Ditto. Internal cast of cardinal region of same shell. x 1\. 



Fig. 28. Stropheodonta Jamesoni, sp. nov. Brachial valve. x 1|. Saugh Hill Group, Woodland 

 Point. G. (Figured, Davidson, Suppl., pi. xv, fig. 25.) 



Fig. 29. Ditto, ditto. xl|, Same horizon and locality. G. 



Fig. 30. Ditto. Cardinal region of pedicle-valve, showing minute denticulations. x 3. Same horizon 

 and locality. G. 



