PLATE 32. 



F)V. 1. 155. 2. Orthis testcdinaria. (Pag. 117.) 



1 II. Ventral valve. 1 I'. Profile view of the shell. 1 c. Dorsal valve. 1 d. Canlinal view of shell. 



1 c. A smaller specimen. 1 /. Interior of the dorsal valve. 1 g. Interior of the venti-al valve. 



1 h. Cast of the dorsal valve. 1 i, /•% I- The same species from the Blue limestone of Ohio. 



Pier. 2. 156. 3. Orthis stib.«:(1uata. (Pag. 118.) 



2 a. Ventral valve. 2 b. Dorsal valve. 2 c. Profile view. 2 d. Cai-dinal view. 



2 e,f. Figures of a smaller specimen; the ventral valve being less convex than in the older specimen. 



pjg, 3. 157. 4. Orthis bellarugosa. (Pag. 118.) 



3 a. Ventral valve. 3 ft. Dorsal valve. 3 c. Profile view. 3 d. Cardinal view. 



3 e. An enlarged portion of the surface, showing the imbricating squamose lamellae. 



Fio-. 4. 158. 5. Orthis disparilis. (Pag. 119.) 



4 a. Ventral valve. 4 6. Dorsal valve. 4 c. Profile view. 4 d. Cardinal area and foramen. 



Fio-. 5. 159. 6. Orthis perveta. (Pag. 120.) 



5 a. Ventral valve. rj ft. Cardinal view. 5 c. Profile view. 5 d. Cardinal view magnified. 



Fio-. 6. 160. 7. Orthis tequivalvis. (Pag- 120.) 



G a. Ventral valve. 'i ft. Dorsal valve. 6 c. Cardinal view, showing the equality of the valves. 



Fig. 7. 161. 8. Orthis fissicosta. ^ (Pag. 121.) 



7 a. Ventral valve. 7 ft. Profile view, showing the projecting beak of the doi-sal valve. 



Fiff. 8. 162. 9. Orthts TRICENAKIA. (Pag. 121.) 



S a. Ventral valve and area. 8 A. Intei-ior of the dorsal valve. 8 c. Exterior of the dorsal valve. 



8 (/. Interior of the ventral valve. 8 e. Profile view of a perfect specimen. 



Fig. 9. 163. 10. Okthis plicatella. (Pag. 122.) 



U rt, ft, c. Ventral valves. 9 d. Profile view of the last. 9 c. Cardinal view of the same, 



fl/. 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 ft. Dorsal valve of the same specimen. 

 10 c. Cardinal view of another specimen. 10 d. Ventral valve. 10 e. Interior of tlie ventral valve. 



Fin-. 11. 165. 12. Orthis pectinella, var. semiovalis. (Pag. 124.) 



11. .\ large specimen, somewhat imperfect. 11 o, ft. Dorsal and ventral valve of a smaller individual. 



Fig. 12. 166. 13. Orthis insculpta. (Pag. 125.) 



12 a. Dorsal valvl^ thi' beak imperfect. 12 A. Interior of tlie dorsal valve. 12 c Dorsal area. 



Fig. 13. 167. 14. Orthis dichotoma. (Pag. 125.) 



13 «. \'entral valve, showing the projecting dorsal beak. 13 ft. Profih' view of the sami'. 



