PLATE 31 B. 



Fig;. 1. 145. 8. LeptjEna alternistriata. (Pag- 109.) 



1 a. Dorsal valve of a large specimen, showing a very regular alternation in the size of the striie, 

 1 b. Ventral valve of the same specimen, the strise being regular and uniform in size. 



1 c. A smaller specimen, presenting a greater extension of the cardinal extremities, and an irregular alterna- 



tion of the strise upon the surface. 



Fig. 2. 146. 9. Lept^na sericea. (Pag- 110.) 



2 a, b. The form and surface of the shell are perfectly preserved in this specimen, both valves of which have 



distinct larger striic alternating with several smaller ones. 

 2 c, d. The opposite valves of another specimen, showing the equal strise and a few' concentric lines of growth. 

 2 e. Interior of the ventral valve, showing two winglike papillose callosities for the visceral attachment. 

 'If, shows a variation from the preceding internal structure. 

 2 g. Interior of the convex valve, showing the visceral impression, margined by a sharp elevated ridge. 



2 h. View of the cardinal area of the convex valve, showing the deltoid aperture which is partially closed. 



Fig. 3. 147. 10. Lept^ina filitexta. (Pag. 111.) 



3 a. Ventral valve of a large specimen. 3 b. Cardiiial area. 3 c. Interior of the dorsal valve. 



3 d. Dorsal valve of a smaller specimen. 3 c. Cardinal view of tlie same. 

 3/. An enlarged portion of the surface, showing tlie textile character. 



Fig. 4. 148. 11. Lept^ena plandmbona. (Pag. 112.) 



4 a & i. Views of the two valves ; the ventral one b showing some strong imbricating lines of growth. 

 •1 c. Cardinal view, showing the nearly linear area and closed foramen. 



■1 (/. Interior of the concave valve. 4 c. Lateral view of the shell. 



Fig. 5. 149. 12. Lept.i:na deflecta. (Pag. 113.) 



5 a Dorsal valve of the specimen. Ti b. Cardinal area of the same. 



Fig. 6. 150. 13. Left, ena recta. (Pag. 113.) 



t'l a. View uf the ventral valve. ' •) b. Cardinal view of the same shell. 



Fig. 7. 151. 14. Lept^na planoconvexa. (Pag. 114.) 



1 a. View of the dorsal valve, with one of the cardinal extremities produced beyond the other. 



7 6. A smaller specimen. 7 c. Profile view of the shell. 7 d. Cardinal view of the first specimen. 



Fig. 8. 152. 15. Lept^na tenuilineata. (Pag- 115.) 



Fig. 9. 153. 16. LEPT.a;NA subtenta. (Pag- 115.) 



;• a. View of the dorsal valve, i) J. Interior of the hinge margin. 



Fig. 10. 154. 17. Luns.'eiA {Species U7idetermined). (Pag- 116.) 



10 a. Ventral valve, showing the equal radiating stris. 10 ft. Dorsal valve, with unequal striae. 



10 e. Cardinal area, and the same enlarged, showing the open foramen and imperforate beak. 



