PLATE 31 B. 
K,g. 
Fig. 
Fig. 
Fie. 
Fie. 
Fie. 
Fig. 
Fig. 
Fig. 
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 striae, 
1 b. Ventral valve of the same specimen, the striae being regular and uniform in size. 
1 t. A smaller specimen, presenting a greater extension of the cardinal extremities, and an irregular alterna¬ 
tion of the striae upon the surface. 
2. 146. 9. Leptjena 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 striae alternating with several smaller ones. 
2 c, d. The opposite valves of another specimen, showing the equal striae and a few concentric lines of growth. 
2 e. Interior of the ventral valve, showing two winglike papillose callosities for the visceral attachment. 
2 /, 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. 
3. 147. 10. LEPTiENA FILITEXTA. (Pag. 111.) 
3 a. Ventral valve of a large specimen. 3 b. Cardinal area. 3 c. Interior of the dorsal valve. 
3 d. Dorsal valve of a smaller specimen. 3 e. Cardinal view of the same. 
3/. An enlarged portion of the surface, showing the textile character. 
4. 148. 11. LEPTiENA PLANUMBONA. (Pag. 112.) 
4 a Si, b. Views of the two valves ; the ventral one b showing some strong imbricating lines of growth. 
4 c. Cardinal view, showing the nearly linear area and closed foramen. 
4 d. Interior of the concave valve. 4 e. Lateral view of the shell. 
5. 149. 12. LEPTiENA DEFLECTA. (Pag. 113.) 
5 a. Dorsal valve of the specimen. 5 b. Cardinal area of the same. 
6. 150. 13. Lept/ena recta. (Pag. 113.) 
6 a. View of the ventral valve.*' 6 b. Cardinal view of the same shell. 
7. 151. 14. Lept^ina planoconvexa. (Pag. 114.) 
7 a. View of the dorsal valve, with one of the cardinal extremities produced beyond the other. 
7 b. A smaller specimen. 7 c. Profile view of the shell. 7 d. Cardinal view of the first specimen. 
8. 
152. 
15. 
LEPTiENA cTENUILINEATA. 
(Pag. 
115.) 
9. 153. 
9 a. View of the dorsal valve. 
16. 
LePTjENA subtenta. 
9 b. Interior of the hinge margin. 
(Pag. 
115.) 
10. 
154. 
17. 
Lept7ena ( Species undetermined). 
( Pag- 
116.) 
10 a. Ventral valve, showing the equal radiating striae. 10 b. Dorsal valve, with unequal striae. 
10 c. Cardinal area, and the same enlarged, showing the open foramen and imperforate beak. 
