PLATE 4 (bis). 
Fig. 1. 28. 1. Leprmna PLiciFERa. (Pag. 19.) 
1 a. Figure of the convex valve. 
1b. Cast of convex valve, with a portion of the shell remaining : cast of visceral cavities magnified. 
Fig. 2. 29, 2. LeEprmNa INCRASSATA. A (Pag. 19.) 
2 a, b. Convex valves of this species. 2c. Ventral valves. 
2d. Cast of the interior of the convex valve, and the same enlarged. 
Fig. 3. 30. 3. LEPTzNA FASCIATA. (Pag. 20.) 
3 a, b. Convex valves of two individuals. 3c. A larger specimen of the same. 
Fig. 4. 31. 1. OrruHts cosTatis. (Pag. 20.) 
4 a. An imperfect shell, showing the radii towards the margin. 
4 6, A cast showing the visceral marking, and casts of radii near the base of the shell. 
4c. An impression of the convex valve, smaller than the other specimens. Such impressions are abundant. 
Fig. 6. 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. 7b. Lateral view of the same individual. 
7c. Dorsal valve of a small specimen. 
7d. Front view of a large specimen. 7 e. Dorsal valve of the same. 
Fig. 8. 35. 4. ATRYPA PLICIFERA. (Pag. 22.) 
8 a,b. View of ventral valve, and front of same individual. 
8 c,d. Ventral valve and front view of another individual. 
Fig. 9. 36. 5. ATRYPA ALTILIS. (Pag. 23.) 
9 a. View of the ventral valve, showing the beak of the dorsal valve. 9 b. View of the dorsal valve. 
9c. Lateral view of the same shell. 9 d. Front view, showing the elevation of the mesial radii. 
Fig. 10. 37. 1. OnrpicuLa? DEFORMIS. (Pag. 23.) 
Fig. 11. 38. 1. Metoproma? pusta. (Pag. 23.) 
Fig. 12. 39. 1. ILLaZNUS aRctURUS. (Pag. 23.) 
Fig. 13. 40. 2. Ituenus crassicaupa ? (Pag. 24.) 
Fig. 14. 41. 1. Asapuus? optusus. (Pag. 24.) 
Fig. 16. 42, 2. ASAPHUS MARGINALIS. (Pag. 24.) 
Fig. 16. - 43. 1. IsoreLus cicas? . (Pag. 25.) 
Fig, 17, 18, 19. 44, 2. IsoTELUS CANALIS. (Pag. 25.) 
18 & 19. Labrum or epistoma of an Isotelus, perhaps of I. canalis. 
Fig. 20. 45. 1. Crraurus? (Species undetermined). (Pag. 25.) 
Fig. 21. A fragment of the crust of an unknown trilobite. 
