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PLATE 38. 



Fig. 1. 74. 7. Pleurotomakia umbilicata. " {^f-g- 176.) 



1 a. Back of the shell, showing an elevated spire. 1 b. Front view, showing the aperture. 1 c. Base. 

 I </. Top of the spire of a larger specimen. 1 e. Front view, showing a depressed spire. 1/. Base. 

 1 g. Specimen from Mineral Point, showing a greater elevation of the spire. 



Fig. 2. 226. 14. Pleurotoiiaria indknta. (Pag- 176.) 



Fig. 3. 227. 15. Pleueotomaeia ambigua. (Pag- 1''6.) 



3 a. View of the back of the spire. 3 b. Front of the same, showing the aperture. 



Fig. 4. 228. 16. Pleuhotomaria percarinata. (Pag- 177.) 



Fig. 6. 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 e. 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/. A smooth cast from crystalline limestone, scarcely preserving the upper carination in an obscure angle. 



6 g. A large imperfect specimen, still preserving the striie upon the surface. 



5 A. A portion of the same enlarged. 



Fig. 6. 230. 7. MuBcmsoNiA tkicaeinatx. (Pag. 178.) 



C 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 tlie 



carina sharply projecting. 



Fig. 7. 231. 8. MtmcHisoNiA peeangxtlata. (Pag- ^79.) 



7 a. Back of the spire, showing six volutions. 7 6. A portion of the surface, with the stris enlarged. 



Fig. 8. 232. 9. Mitechisonia uniangulata. (Pag. 179.) 



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