PLATE XXVII. 



Fig. i. Mactra (Mactrotomd) fragilis Gmelin, right valve from below, showing the pro- 

 file of the hinge-teeth : a, anterior ventral, and b, anterior dorsal lamina ; 



c, accessory lamella of, if, anterior arm of the right cardinal tooth, and f, 

 posterior arm of the same ; the space between the teeth a, c, d, c and the 

 edge of the chondrophore is the ventral sinus, that between a and b is the 

 anterior sinus ; f, septum between the ligament (attached to the shell at if) 

 and the rcsilium ; // and / are the ventral and dorsal posterior lamina' 

 respectively ; about 60 mm. ; p. 876. 



Fig. 2. Spisula (Hcinimactra) citrlidcns Dall, outline of young shell traced from incre- 

 mental lines on broken larger valve ; 35 mm. ; p. 898. 



f'S- 3- Spisula (Hfiniinactni) subpotlderosa Orbigny, profile of hinge from above, left 

 valve : a, anterior lateral ; /;, cardinal tooth ; c, accessory lamella ; d, spur 

 with part of the cavity for the sagittate ligament below it ; c, scar of attach- 

 ment of ligament ; f, posterior lateral lamina ; 70 mm. ; p. 878. 



Fig. 4. Mactra (Mactrotoma) fragilis Gmel., part of right valve showing hinge: a, 

 anterior dorsal lamina ; f, anterior ventral lamina ; b, accessory lamella of, 

 f, anterior arm (t, posterior arm) of the right cardinal ; d, septum between 

 the resilium and ligament ; -c, ligamentary scar ; p. 876. 



Fig. 5. Teinosloma (Solariorbis) jloi'idannin Dall, 1 895, 'upper surface ; 1.6 mm. 



Fig. 6. The same, lower surface ; Pliocene of the Caloosahatchie beds. 



Fig. 7. Spisula (Mactnuncris) dodona Dall, exterior of right valve ; Oak Grove, Florida ; 

 50 mm. ; p. 896. 



Fig. 8. Mactra (Alactrotoina) Jragilis Gmel., left valve, profile of hinge-plate : a, 

 anterior lamina ; /;, accessory lamella ; c, cardinal tooth ; d, septum ; f, 

 posterior lamina ; p. 876. 

 . Fig. 9. Teinosloma (Solariorbis) Jloridanuin Dall ; 1.6 mm. 



Fig. 10. Teinosloma (Solariorbis) undiila Dall, 1895 ; from Natural Well of Duplin 

 County, North Carolina ; 2.5 mm. 



Fig. II. The same, from above ; Miocene. 



Fig. 12. Teinostoma (Solariorbis) ihiplincnsc Dall, 1895; Miocene; from below ; 2mm. 



Fig. 13. Spisula (Mactroineris) dodona Dall, hinge-plate of left valve ; 30 mm. ; p. 878. 



Fig. 14. Mactrclla alata Spengler, hinge-plate of left valve : a and /;, posterior lamina- ; 

 f, scar of ligament above septum ; d, spur ; posterior and anterior sides of 

 cardinal tooth are supported by, e, septal buttresses ; s, anterior sinus ; /, 

 anterior lamina ; 57 mm. ; p. 877. 



Fig. 15. Teinostoma (Solariorbis) duplinense Dall, from above ; diam. 2 mm. 



Fig. 16. Spisula (Hciniinaitra) stikpondcrosa Orbigny, hinge-plate of left valve : a, 

 dorsal, and c, ventral posterior lamina: ; b, ligamentary scar not separated 

 from the pit below by a septum ; c, spur ; /", accessory lamella ; /, petaloid 

 cardinal tooth ; d, anterior lamina with s, absorption scar, from ventral 

 lamina of opposite valve ; 70 mm. ; pp. 878, 899. 



Fig. 17. Teinostoma (Solariorbis) itndiila Dall, from below ; 2.5 mm. 



Fig. 18. Mactra {Mactrotoma) fragilis Gmelin, hinge-plate of left valve : a, posterior 

 lamina ; b, ligamentary scar with septum below it ; c, spur, roofing the pit ; 



d, cardinal tooth with e, accessory lamella, and f, anterior lamina ; p. 876. 

 Fig. 19. Mactra chipolana Dall, hinge-plate of left valve : -a, dorsal, and c, ventral 



posterior lamina ; b, ligamentary scar ; c, spur ; f, anterior arm of cardinal 

 tooth ; d, anterior lamina ; the septum is not shown very clearly, being 

 seen on edge ; p. 892. 



Fig. 20. Labiosa (Racta*) a/fa Conrad, exterior of right valve ; 65 mm. ; p. 907. 



Fig. 21. Tcinostoiiui (Solariorbis) duplinense Dall ; 2 mm. 



Fig. 22. Spisula (Hcniimactra~) dcnsa Dall, exterior of left valve ; Oak Grove, Florida ; 

 14 mm. ; p. 900. 



Fig. 23. Labiosa (Racta) alta Conrad, hinge-plate of left valve : f, anterior lamina ; c, 

 ligament scar with septum below it ; /', cardinal tooth with one arm project- 

 ing over the chondrophore ; a, anterior lamina ; 33 mm. ; p. 907. 



Fig. 24. Spisula (Hcmiinactra) curtidcns Dall, hinge-plate of right valve : a, dorsal, and 

 e, ventral anterior lamina; ; b, anterior arm of cardinal tooth ; c, ligament scar, 

 without septum below it ; d and f, posterior lamina} ; 44 mm. ; p. 878. 



Fig. 25. Spisula (Mactroineris) dodona Dall, hinge-plate of right valve ; 30 mm. ; p. 896. 



Fig. 26. Spisula dcluinbis Conrad ; Suffolk, Virginia ; interior of right valve ; 96 mm. ; 

 p. 897. 



Fig. 27. Gyrodisca diiplincn sis Dall, 1895; Upper Miocene ; 3.6111111. 



/^ Fig. 28. Modiolus tainpacnsis Dall ; from liallast Point silex beds ; interior of right 

 valve ; 22.5 mm. ; p. 793. 



Fig. 29. Spisula ma^nol/ana Dall, interior of left valve ; 19 mm. ; p. 899. 



9 22 



