PLATE 32. 
FiV. i. 155. 2. Orthis testudinaria. (Pagl H?.) 
1 a. Ventral valve. 1 b. Profile view of the shell. 1 c. Dorsal valve. 1 d. Cardinal view of shell. 
1 e. A smaller specimen. 1 /. Interior of the dorsal valve. 1 g. Interior of the ventral valve. 
1 h. Cast of the dorsal valve. 1 i, k, l. The same species from the Blue limestone of Ohio. 
Fio-. 2. 156. 3. Orthis subjequata. (Pag- H8.) 
2 a. Ventral valve. 2 b. Dorsal valve. 2 c. Profile view. 2 d. Cardinal view. 
2 e, f. Figures of a smaller specimen ; the ventral valve being less convex than in the older specimen. 
Fig. 3. 157. 4. Orthis bellarugosa. (Pag- 118.) 
3 a. Ventral valve. 3 b. Dorsal valve. 3 c. Profile view. 3 d. Cardinal view. 
3 e . An enlarged portion of the surface, showing the imbricating squamose lamellae. 
Fig. 
4. 
158. 
5. Orthis 
disparilis. 
(Pag. 119.) 
4 a. Ventral valve. 
4 b. 
Dorsal valve. 
4 c. Profile view. 4 d. Cardinal area and foramen. 
Fig- 
5. 
159. 
6. Orthis 
PERVETA. 
(Pag. 120.) 
5 a. Ventral valve. 
5 b. 
Cardinal view. 
5 c. Profile view. 5 d. Cardinal view 
magnified. 
Fig. 
6. 
160. 
7. Orthis 
A2QUIVALVIS. 
(Pag. 120.) 
6 a. Ventral valve. 
6 b. 
Dorsal valve. 
6 c. Cardinal view, showing the equality of 
the valves. 
Fig- 
7. 
7 a. Ventral valve. 
161. 
7 b. 
8. Orthis fissicosta. 
Profile view, showing the projecting beak of the dorsal valve. 
(Pag. 121.) 
Fig. 
8. 
162. 
9. Orthis 
TRICENARIA. 
(Pag. 121.) 
8 a. Ventral valve and area. 8 b. Interior of the dorsal valve. 8 c. Exterior of the dorsal valve. 
8 d. Interior of the ventral valve. 8 e. Profile view of a perfect specimen. 
Fig. 9. 163. 10. Orthis plicatella. (Pag. 122.) 
9 a, b, c. Ventral valves. 9 d. Profile view of the last. 9 e. Cardinal view of the same. 
9 f Ventral valve of a large specimen. 9 g. Profile view of the same. 
Fig. 10. 164. 11. Orthis pectinella. (Pag. 123.) 
10. A small individual. 10 a. Ventral or convex valve. 10 b. Dorsal valve of the same specimen. 
10 c. Cardinal view of another specimen. 10 d. Ventral valve. 10 e. Interior of the ventral valve. 
Fig. 11. 165. 12. Orthis pectinella, var . semiovalis. (Pag. 124.) 
11. A large specimen, somewhat imperfect. 11 a, b. Dorsal and-ventral valve of a smaller individual. 
Fig. 12. 166. 13. Orthis insculpta. (Pag. 125.) 
12 a. Dorsal valve, the beak imperfect. 12 b. Interior of the dorsal valve. 12 c. Dorsal area. 
Fig. 13. 167. 14. Orthis dichotoma. (Pag. 125.) 
13 a. Ventral valve, showing the projecting dorsal beak. 13 b. Profile view of the same. 
