980 D\l F. R. C. REED ON THE 



Plate VII. 



Fig. 1. Orthis (Plectorthis) thrawensis, sp. nov. Brachial valve (from squeeze of impression). xl|. 

 Starfish Bed, Drummuck Group, Thraive Glen. G. 



Fig. 2. Orthis (Dinorthis) flabellulum, Sow., var. nov. carrickensis. Pedicle-valve. Nat. size. Stinehar 

 Limestone Group, Craighead. G. (Figured, Davidson, Suppl., pi. xi, fig. 5.) 



Fig. 3. Ditto. Brachial valve. Nat. size. Same horizon and locality. G. (Figured, ibid., pi. xiii, 

 %. 3.) 



Fig. 4. Ditto. Internal cast of pedicle-valve, x 1£. Balclatchie Group, Ardmillan. G. 



Fig. 5. Ditto. Impression of exterior of pedicle-valve. x 1£. Same horizon, Balclatchie. G. 



Fig. 6. Ditto. Internal cast of same shell, x 1^. G. 



Fig. 7. Orthis (Dinorthis) porcata, M'Coy. Internal cast of brachial valve. x 1|-. Starfish Bed, 

 Drummuck Group, Thraive Glen. G. 



Fig. la. Ditto. Posterior view of same specimen. x 1-L 



Fig. 8. Ditto. Internal cast of cardinal and muscular area of brachial valve. x 2£, Same horizon 

 and locality. G. 



Fig. 9. Ditto. Internal cast of pedicle-valve. x \\. Same horizon and locality. G. 



Fig. 10. Ditto. Same pedicle-valve (from squeeze of impression). x \\. G. 



Fig. 11. Ditto. Left half of brachial valve (from squeeze of impression). xl|. Same horizon and 

 locality. G. 



Fig. 12. Ditto. Median vertical section through complete internal cast. x 1J. Same horizon and 

 locality. G. 



Fig. 13. Orthis (Hebertella) balclatchiensis, Dav. Pedicle-valve. x 2. Balclatchie Group (conglom.), 

 Balclatchie. G. 



Fig. 13a. Ditto. Outline side-view of same specimen, x 2. 



Fig. 14. Ditto. Pedicle-valve. x 2. Same horizon and locality. G. 



Fig. 15. Ditto. Brachial valve (from squeeze of external impression). x 2. Balclatchie Group, 

 Ardmillan. G. 



Fig. 16. Ditto, ditto, x 2^ (from squeeze). Same horizon and locality. G. (Figured, Davidson, 

 Suppl., pi. xiii, fig. 8.) / 



Fig. 17. Ditto. Brachial valve. x 2. Stinehar Limestone Group, Craighead. G. 



Fig. 18. Ditto. Internal cast of posterior portion of pedicle-valve. x 2|-. Balclatchie Group, 

 Balclatchie. G. 



Fig. 19. Ditto. Internal cast of pedicle-valve. x 2|-. Same horizon, Ardmillan. G. 



Fig. 20. Ditto. Internal cast of median cardinal region and muscular area of brachial valve, x 2|. 

 Same horizon and locality. G. 



Fig. 21. Orthis (Hebertella) bellatrix, sp. nov. Impression of exterior of brachial valve. x 1|. 

 Balclatchie Group, Dow Hill. G. 



Fig. 22. Ditto. Median transverse section of complete internal cast of same shell. x 1J. G. 



Fig. 23. Ditto. Brachial valve. x lj. Balclatchie Group (conglom.), Balclatchie. G. 



Fig. 24. Ditto. Complete shell, pedicle-valve. x li. Same horizon and locality. G. 



Fig. 24a. Ditto. Outline side-view of same specimen. x li 



Fig. 25. Ditto. Impression of exterior of brachial valve. x 1£. Balclatchie Group, Balclatchie. G. 



Fig. 26. Ditto. Internal cast of same shell. x 1|. G. 



Fig. 27. Ditto. Impression of exterior of pedicle-valve. x 1£. Same horizon and locality. G. 



Fig. 28. Ditto. Internal cast of pedicle.-valve. x 1|-. Same horizon and locality. G. 



Plate VIII. 



Fig. 1. Orthis (Hebertella) bellatrix, sp. nov. Internal cast of pedicle-valve. x 1-L Balclatchie Group, 

 Balclatchie. G. 



Fig. 2. Ditto. Internal cast of brachial valve. x 1L Same horizon and locality. G. 



