TAB. X. 



Fig. 



1. Area tetragona, page 76. 



a. outside view of specimen from 



Red Crag. 



b. inside view of the same. 



c. outside of abraded specimen, 



with a sinuate d form of ven- 







tral margin (Bissoarca). 



d. inside of var. Britannica. 



2. Area lactea,j. 78. 



a. outside, left valve. 



b. inside of the same. 



3. Area pectunculoides, jo. 79. 



a. outside of var. brevis. 



b. inside of var. elongata. 



4. Nucinella miliaris, jy. 73. 



a. inside of right valve. 



b. inside of left valve. 



c. united valves, showing the posi- 



tion of the ligament. 



5. Nucula tenuis, p. 84. 



6. Nucula nucleus, p. 85. 



Fig. 



8. 



9. 

 10. 

 11. 



12. 

 13. 

 14. 

 15. 

 16. 



17. 



Nucula trigonula, p. 86. 

 Nucula Isevigata, j. 81. 

 Nucula Cobboldiae, p. 82. 

 Leda semistriata,jo. 91. 



Leda pygmsea, j. 95. 



a. inside view of an acuminated 



specimen. 



b. outside of a specimen of a 



more rounded form. 



Leda caudata,jo. 92. 

 Leda pernula, p. 93. 

 Leda truncata, p. 94. 

 Leda Thraciseformis, p. 96. 

 Leda lanceolata, j. 88. 



Leda myalis, p. 90. 



c. outside view of elongated var. 



The lines indicate the size of the specimens. 



