1^1. A 'I'M XXVTI. 



TkI.I.IXA (i-dittilinnl). 



Figs. 



1. T. stridtKluidi's, 8tol. Upper Greensand, Hlackdowii. IJi'itisli ]\ru.s('uiii, 

 No. L 1G829. Hinge of right valve. X 2. (P. 172.) 



2-8. 'T. (Pdlceomcera) ina'qiiali>s, Sow. Upper Greensand, Blackdown. Sedgwick 

 Museum, except fig. 8. (P. 173.) 



2. Right valve. 



3 a, right valve ; h, part of postero-dorsal area, x 4. 

 4, 5. Left valves. 

 ('). Dorsal view. 



7 ((, interior of left valve ; h, hinge of same, x 2. 

 8. British Museum, No. L 1712i>. Hiuge of right valve, x 2. 



9. T. (Linearia), sp. Lower Greensand (Crackers), Atlierfield. British 

 Museum, No. 48626. Left valve, X li. (P. 175.) 



10-13. T. {Linearia) suhtetiiiixlri(ttii^ {['ijvh. Upper Greensand, Blackdown. (P. 

 175.) 



10 British Museum, No. L 7129. a, left valve, x \\; h, dorsal view, x \\. 



11. Sedgwick Museum. Left valve, x 1^. 



12. British Museum, No. L ]712!t. Right valve, x U. 



13. British Museum, No. L 1712t>. Hiuge of right valve, x 2. 



14-10. T. (Lluearld), sj). Upper Greensand, Blackdown. British Museum, No. 

 L 17129. (P. 177.) 



14. Right valve, x 1|. 



15. Left valve. 



1(3. Dorsal view, x li. 



Gcintfi — M.VCTKA, Liintasus. 



17,18. M. sp. Lower Greensand (Ferruginous Sands), Shanklin. Sedgwick 

 Museum. 17 «, left valve; 1 7 />, dorsal view. 18, portion near the 

 middle of valve, X (J. (P. 177.) 



19-23. M. anyiilata, Sow. Upper Greensand, Blackdown. (P. 177.) 



19. Museum of Practical Geology, No. 20714. a, right valve, x l\; b, dorsal 



view, X l\. 



20. Sedgwick Mu.seum. Left valve, x li. 



21. Sedgwick Museiuu. «, left valve, x I5; t, posterior view of same, X 1|. 



22. Sedgwick Museum. Right valve. 



23. Museum of Practical Geology, No. 20717. Hiuge of left valve, x 3. 



Gru IIS — Ptychomya, Ac/assiz. 

 24-26. P. IhihiudhViiKt (d'Orl).). Jiower Greensand. Sedgwick Museimi. (P. 

 ] 79.) 



24. Perna-bed, Atherlield. n, riL,dit valve; h, dorsal view. 



25. P«rH,(-l.ed, Atherlield. Left' valve. 



2(j. Ferruginous Sands, Shanklin. Hiuire of ri'dit valve. 



