PLATE XXVill. 



Cicuns — DosiNlOl'Sis, Con rail. 



Figs. 

 1 — (5. D. xnhrohuiiJii (Sow.). Upper Grecnsaiul, BlucktUnvu. Sedgwick 

 Museiun, C;iiul)i'i(lge ; except fig. 2, Dritisli .Must^uiii, Nn. LI7"<)7. 

 (P. 181). 



1, 2, 6. Right valves. 



3. Interior of right valve x Is. 

 4, 5. Left valves. 5 6, iuterior of 5 o. 



7 — 1'). D. cfiperatd (Sow.). Upper Giveiisaud, Blackdowii. Sfdgwiclc Museum. 

 (P. 182). 



7,8. Eight valves. 7 L, hinge x I.t. 

 'J, 10. Left valves. 10 h, iuterior of 10 a ; 10 c, dorsal view. 



Genus — CYruiMERi.v, Coii.vdil. 



11 — 18. C (Cijrl(ji-i,sm(i) vcclrusis (Forbes). Lower Greeiisaud (Crackers), 

 Athcrfield. Sedgwick Museum. (P. 183.) 



11, 12. Right valves. 11 //, dorsal view of 11 a. 



IS, 14. Hinges of right valves. LJ, a small speeiineu x 2. 



15, U;. Left valves. 



17. Hiuge of left valve x Is. 



18. Internal cast of right valve. Exact hori/oii not iaiowu. 



1'.) — 23. G. {Gi/clorifinia) jxirrn (Sow.). Lower Grcensand (Cracker.s), Atliei'Held. 

 Sedgwick Museum. (P. 184) 



19 a, right valve ; b, dorsal view of both valves. 

 20. Hinge of right valve x 3. 

 21 — 23. Left valves. 21 b, j)art of 21 a near the ventral iiiargiu x 4. 



