PLATE 38. 
Fig. l. 
74. 7. Pleurotomaria umbilicata. 
(Pag. 175.) 
1 a. Back of the shell, showing an elevated spire. 1 b. Front view, showing the aperture. 1 c. Base. 
1 d. Top of the spire of a larger specimen. 1 e. Front view, showing a depressed spire. If. Base. 
1 g. Specimen from Mineral Point, showing a greater elevation of the spire. 
Fig. 2. 
226. 
14. 
Pleurotomaria indenta. (Pag- 176.) 
Fig. 3. 
227. 
15. 
Pleurotomaria ambigua. (Pag- 176.) 
3 a. 
View of the back of the 
spire. 
3 b. Front of the same, showing the aperture. 
Fig. 4. 
228. 
16. 
Pleurotomaria percarinata. (Pag. 177.) 
Fig. 5. 
229. 
6. 
Murchisonia bicincta. (Pag- 177.) 
5 a. Front view of a nearly perfect specimen, showing the form of the aperture. 5 b. Back view. 
5 c. Front view of a specimen with the last volution broken off behind the aperture. 
5 d. View of an imperfect specimen, showing the direction of the striae. 5 e. Enlarged view of the same. 
5 f A smooth cast from crystalline limestone, scarcely preserving the upper carination in an obscure angle. 
5 g. A large imperfect specimen, still preserving the striae upon the surface. 
5 h. A portion of the same enlarged. 
Fig. 6. 230. 7. Murchisonia tricarinata. (Pag. 178.) 
6 a. View of the back of the shell. 
6 b. Front view, showing the aperture, which is imperfect on the outer side. 
6 c. A fragment apparently belonging to the same species ; but the striae are much better preserved, and the 
carinae sharply projecting. 
Fig. 7. 231. 8. Murchisonia perangulata. (Pag. 179.) 
7 a. Back of the spire, showing six volutions. 7 b. A portion of the surface, with the striae enlarged. 
Fig. 8. 
232. 
9. 
Murchisonia uniangulata. 
(Pag. 179.) 
