SUPPLEMENT, PLATE V. 



SILURIAN AND CARBONIFEROUS. 



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



Fig. 



1 — 4. Duyia navicula, Sow., sp. la,b. Exterior, enlarged. 2. Lateral aspect, nat. size. 2a,b,c. 



Enlarged, showing ventral, dorsal, and lateral aspects of spirals, 

 loop, and attachments to hinge-plate. 3. Large specimen, 

 lateral aspect, nat. size. 3 a. The same enlarged. 4, 4 a, b. The 

 same as 2a,b,c, as they would appear if free from matrix. 

 Ludlow shales, Shropshire. (P. 96.) 



5, 6. IVhitJieldia tumida, Dal., sp. 5. Interior of dorsal valve, enlarged, showing spirals, attachments 



to the hinge-plate, and forked loop. 5 a. Profile of the same, 

 enlarged, showing one of the spirals, the primary lamella of the 

 other spiral, attachments of primary lamellae to hinge-plate, and 

 forked loop. 6. Meristina Maria, Hall, an American specimen, 

 to show that it is the same genus and species as W. tumida, Dal. 

 Developed by Mr. Glass from a typical specimen of Prof. Hall's 

 species forwarded by him. (P. 107.) 



7, 8,9. Meristella arcuata, Hall. Given here for comparison with JVhitJieldiaani Merista. 7. Interior 



of ventral valve to show there is no shoe-lifter process. 8. Pro- 

 file section enlarged, to show one of the spirals, the primary 

 lamella of the other spiral, the attachments of primary lamellae to 

 hinge-plate, and the loop with its rings. Developed from an 

 American specimen sent to Mr. Glass by Mr. Whitfield. 9. 

 Primary lamellaa and loop, much enlarged ; a, b, primary lamellae ; 



c, ring and loop. (P. 106.) 



10 — 13. 3/en5/a //ercw/ea, Barrande, sp. Given here for comparison with Whitfieldia and Meristella. 



10. Back of ventral valve, showing the cavity left by the shoe- 

 lifter process, and showing the spirals. 10 a. Showing the 

 spirals from the dorsal side. 11. Interior of a portion of ventral 

 valve, showing the beak and shoe-lifter process. 12. Specimen 

 as developed by Mr. Glass, showing primary lamellae, attachments 

 to binge-plate, loop, and rings. 13. Interior of the dorsal valve, 

 much enlarged, showing spirals, primary lamellae, loop, rings, and 

 attachments to the hinge-plate. 13 a. A profile section to show 

 position of loop and rings. The shoe-hfter process, as shown by 

 subsequent investigations, should be represented in the figure as 

 being nearer to the attachments of the spirals to the liinge-plate. 

 The above specimens were developed by the Rev. N. Glass from 

 examples of Merista Hereulea, forwarded by Mr. Barrande. 

 (P. 103.) 



14 — 19. Athyris i)lano-sulcata,Vh\\\\^&. Carboniferous, given for comparison. 14. Exterior, nat. size. 



15, 15 a. Ventral and dorsal aspects, enlarged, the shell having 

 been removed so as to expose the spirals, the accessory lamellae, 

 and attachments. 16. Part of dorsal aspect of spirals enlarged, 

 showing, a, first and second ordinary spiral coils ; b, the acces- 

 sory lamellae. 17, \~ a. Front and profile view, showing the 

 primary lamellae and their hook-sbaped attachments to the hinge- 

 plate (a), also showing the loop and the accessory lauiellae. 

 18, 18 a. From another example : a, attachments to hinge-plate ; 

 b, hook-shaped prolongations from attachments to hinge-plate ; 



d, primary lamellaj ; h, roof-shaped process of loop ; f, single 

 curved lamella ; g, bifurcation of the lamella ; q, accessory 

 lamella. 19. Portion of one of the spiral coils with projecting 

 spines, enlarged. All the above examples were developed by the 

 Rev. N. Glass from specimens sent to him by 3Ir. John Tyin 

 from the Carboniferous limestone of Castleton, Derbvshire. 

 (P. 98.) 



