SUPPLEMENT, PLATE IV. 



Spirals and loops developed by the Rev. N. Glass. 

 Ftg. 



1,2,3. Waldheiinia (or Macandrevia) Mawii, Dav. 1,2. Nat. size. \ a,b, 2 a,b,c,d. Enlarged. 



3. Nat. size. 3 a. Interior of dorsal valve enlarged, 

 showing the loop. 3 b. Profile view of loop. 

 Wenlock shales, Shropshire. (P. / 6.) 

 4, -4 a, 6, c, </. „ „ Glassii, Dav. 4. Nat. size. 4a,b,c,d. Enlarged. Lower 



"Wenlock shale, Shropshire. (P. 77.) 

 5,5 a. Merista ? CzVce, Barrande ? Wenlock shale, Shropshire. (P. 105.) 



6, 6 a, 1^, c. Atrypa ? Mawii, Daw. 6. Nat. size. 6a,b,c. Enlarged. Wenlock limestone, Benthall Edge, 



Shropshire. (P. 116.) 



7. „ imbricata. Sow. Wenlock limestone, Benthall Edge. A transverse section to show 



the vertical spirals. (P. 115.) 

 8,8 a. „ asperula,I>a.v. Wenlock limestone, Benthall Edge. (P. 112.) 



9, 10. Spirifera crispa, Linne. 9. Exterior, nat. size. 10. Enlarged, showing spiral coils and the 



lamellae from the primary coils, which form in 

 Spirifera the imperfect loop. Wenlock shales, 

 under Benthall Edge. (P. 80.) 



11. Cyrtia exporrecta, Wahl. Longitudinal section, showing one of the spirals and lamella 



from the primary coil which forms part of the 

 imperfect loop as in Spirifera. (P. 81.) 



12, 13, 14. Retzia Salteri, Dav. 12. A large example. Wenlock shale, Benthall Edge. 13. Dorsal 



aspect enlarged, showing spirals. 14. Ventral 

 aspect enlarged, showing spiral coils, attachment of 

 primary lamellae to the hinge-plate and loop. 14 a. 

 Profile view, showing one of the spirals, the pri- 

 mary lamella of the other spiral attachments to the 

 hinge-plate, and simple loop. Wenlock shales, 

 Shropshire. (P. 92.) 



15 — 18. Nucleospira pisum, Sow. 15,15 a. A large specimen. 16. Dorsal aspect enlarged, showing 



spirals. 17. Ventral aspect, showing spirals, attach- 

 ments to the hinge-plate, and loop. 18. Profile view, 

 showing the hook-shaped attachments to the hinge- 

 plate. (P. 91.) 



19. Retzia (= llhynchospira) evax, Hall. Niagara group. Waldron, Indiana. Longitudinal 



section, showing attachment of the principal lamella 

 to hinge-plate, and loop. Given here for com- 

 parison. (P. 93.) 



20 — 21. Mertstina nilida,\\-ii\\. 20. Exterior, nat. size. 21. Interior of dorsal valve, showing spirals, 



attachments to hinge-plate, and loop, enlarged. 

 21 a. A profile view, showing one spiral, the pri- 

 mary lamella of the other spiral, attachments to 

 hinge-plate, and loop. Niagara group, Waldron, 

 Indiana. Given here for comparison with M. 

 didyma, of winch it is properlv a synonvra. (P. 

 94.) 



22 23 a. , didyma, Dal. 22. Exterior, nat, size. 23. Interior of dorsal valve, showing spirals, 



attachments to hinge-plate, and loop. 23 a. Pro- 

 file view, showing one spiral, the primary lamella 

 of the other spiral, attachments to hinge-plate, and 

 loop. Wenlock shale, Shropshire. (P. 94.) 



24—26. Atkyris laviuscula. Sow. 24. Nat. size. 24 a, 6. Enlarged. 24 c. Beak enlarged to show 



the apical foramen. 25. Enlarged specimen, show- 

 ing spirals, accessory lamella', and hook-shaped 

 attachments to the hinge-plate. 26. Another speci- 

 men, showing spirals. Wenlock limestone, Benthall 

 Edge (P. 101. 



