PLATE 4 (bis). 
Fig-, 1. 28. 1. Leptjena plicifera. (Pag. 19.) 
1 a. Figure of the convex valve. 
1 b. Cast of convex valve, with a portion of the shell remaining : cast of visceral cavities magnified. 
Fig. 2. 29. 2. Leptjena incrassata. (Pag. 19.) 
2 a, b. Convex valves of this species. 2 c. Ventral valves. 
3 d. Cast of the interior of the convex valve, and the same enlarged. 
Fig. 3. 30. 3. Lepttena fasciata. (Pag. 20.) 
3 a, b. Convex valves of tw ; o individuals. 3 c. A larger specimen of the same. 
Fig. 4. 31. 1. Orthis costalis. (Pag. 20.) 
4 a An imperfect shell, showing the radii towards the margin. 
4 b. A cast showing the visceral marking, and casts of radii near the base of the shell. 
4 c. An impression of the convex valve, smaller than the other specimens. Such impressions are abundant. 
Fig. 5. 32. 1. Atrypa dubia. (Pag. 21.) 
Fig. 6. 33. 2. Atrypa acutirostra. (Pag* 21.) 
The two lower figures are of the natural size; the upper one is enlarged. 
Fig. 7. 34. 3. Atrypa plena. (Pag* 21.) 
7 a. View of the ventral valve, showing the beak of the dorsal valve closely incurved over the beak of the 
former. 7 b. Lateral view* of the same individual. 
7 c. Dorsal valve of a small specimen. 
7 d. Front view of a large specimen. 7 e. Dorsal valve of the same. 
Fig. 8. 35. 4. Atrypa plicifera. (Pag* 22.) 
5 a, b. View of ventral valve, and front of same individual. 
S c, d. Ventral valve and front view of another individual. 
Fig. 9. 36. 5. Atrypa altilis. (Pag* 23.) 
It a . View of the ventral valve, showing the beak of the dorsal valve. 9 b . View of the dorsal valve. 
9 c . Lateral view of the same shell. 9 d . Front view, showing the elevation of the mesial radii. 
Fig. 
10 . 
37. 
1 . 
Orbicftla? deformis. 
(Pag. 23.) 
Fig. 
11. 
38. 
1 . 
Mf.toptoma? dubia. 
(Pag. 23.) 
Fig. 
12. 
39. 
1 . 
Ill^nus arcturus. 
(Pag. 23.) 
Fig. 
13. 
40. 
2. 
Illtenus crassicauda? 
(Pag. 24.) 
Fig. 
14. 
41. 
1 . 
Asaphits? obtusus. 
(Pag. 24.) 
Fig* 
15. 
42. 
2. 
Asaphtis marginalis. 
(Pag. 24.) 
Fig. 
16. 
43. 
1 . 
IsOTELUS GIGAS? 
(Pag. 25.) 
Fig. 
17, 
is 
18, 19. 
& 19. Lnbrum 
44. 2. 
or epistoma of an 
IsOTELUS CANALIS. 
Isotelus , perhaps of I . canal is . 
(Pag. 25.) 
F ig. 
20. 
45. 
1 . 
Ceraurus? (Species undetermined). 
(Pag. 25.) 
Fig. 
21. 
A fragment of the erust of 
an unknown trilobite. 
