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, d, anterior arm of the right cardinal tooth, and c, 

 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 g) 

 and the resilium ; h and z are the ventral and dorsal posterior lamina; 

 respectively ; about 60 mm. ; p. 876. 



Fig. 2. Spisiihi i^Hcinimactra) cii?'tidcns Dall, outline of )Oung shell traced from incre- 

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



Fig. 3. Spisula (Hemimactrd) siibpondcrosa Orbigny, profile of hinge from above, left 

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

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

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



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

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

 f, anterior arm (/, posterior arm) of the right cardinal ; d, septum betvveeri 

 the resihum and ligament ; e, ligamentary scar ; p. 876. 



Fig. 5. Teiiiostoma {Solariorbis) floridanum V)2\\, 1895, upper surface ; 1.6 mm. 



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



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

 50 mm. ; p. 896. 



Fig. 8. Mactra {Mactrotoma) fragilis Gmel., left valve, profile of hinge-plate: a, 

 anterior lamina ; b, accessory lamella ; c, cardinal tooth ; d, septum ; c, 

 posterior lamina ; p. 876. 

 Tcinostoma (Solariorbis) floridaiimn Dall ; 1.6 mm. 

 Tcinostoma (Solariorbis') undiila Dall, 1895 ; from Natural Well of Duplin 



County, North Carolina; 2.5 mm. 

 The same, from above ; Miocene. 



'/'ciiiostonia (Solariorbis) dupliiicnsc Dall, 1895 ; Miocene ; from below ; 2 mm. 

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

 Mactrclla alata Spengler, hinge-plate of left valve : a and b, posterior lamina: ; 



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

 cardinal tooth are supported by, c, septal buttresses ; s, anterior sinus ; i, 

 anterior lamina ; 57 mm. ; p. 877. 



Tcinostoma (Solariorbis) ddipliucnse Dall, from above ; diam. 2 mm. 

 Spisula (Hcniimactra) subpondcrosa Orbigny, hinge-plate of left valve : a, 

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

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

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

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

 Fig. 17. Tcinostoma (Solariorbis) undula Dall, from below ; 2.5 mm. 

 Fig. 18. Mactj-a (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 <?, accessory lamella, and /, 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 ; (/, anterior lamina ; the septum is not shown very clearly, being 

 seen on edge ; p. 892. 



Fig. 20. Labiosa (Raeta) alta Conrad, exterior of right valve ; 65 mm. ; p. 907. 



Fig. 21. Tcinostoma (Solariorbis) diiplinensc Dall ; 2 mm. 



Fig. 22. Spisula (/-/cmimactra) densa Dall, exterior of left valve ; Oak Grove, Florida ; 

 14 mm. ; p. 900. 



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

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

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



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

 i', ventral anterior laminje; b, anterior arm of cardinal tooth; c, hgamentscar, 

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



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



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

 p. 897. 



Fig. 27. Gyrodisca duplutensis Dall, 1895 ; Upper Miocene ; 3.6 mm. 



Fig. 28. Modiolus tampaensis Dall ; from Ballast Point silex beds ; interior of right 

 valve ; 22.5 mm. ; p. 793. 



Fig. 29. Spisula magnoliana Dall, interior of left valve ; 19 mm. ; p. 899. 



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