PLATE 83. 



Fig. 1. 236. 13. MuRCHisoNiA gracilis. ( Pag. 303.) 



I a. A specimen (a east) from the calcareous sandstone. I b. A similar cast from the soft shales at Loraine. 



1 c. A fragment of slate, with several small specimens. 



Fig. 2. 363. 14. Mubchisonia umiahgulata, var. abbbeviata. ( Pag. 304.) 



2 a,b. Two specimens which preserre a part of the shell. . 



3 c A portion of the surface of the last volution magnified, showing the double spiral band. 

 2d. A specimen with the volutions more acutely angulated, but apparently identical. 



Fig. 3. 226. 13. Pleukotomaria subconica. (Pag. 304.) 



3 o. A specimen preserving the vertical striae. 3 6. A portion of the same enlarged. 



3 e, d. IraperCecl casts, from the shales of the Hudson-nver group. 



3 e. A more perfect cast of the same species, from Wisconsin. 



Fig. 4. 364. 17. Pleueotomaria [?] bilix. (Pag. 305.) 



4 a. A small specimen of this species, showing the back of the spire, and the expansion of the last volution 



towards the aperture. 

 Ab. A portion of the surface enlarged, showing the alternating larger and smaller carinae, which are crossed 



by the oblique fine striae. 

 i e. A larger specimen : a view from the outside obliquely into the aperture. 

 4 d. Another specimen, showing the form of the aperture, which is entire on the outer margin. 

 4 e. The base, viewed in the direction of the spire. 



Fig. 5. 365. 18. VvE.xyB.otouK'a.ijL {^Speciet uTidetermined). (Pag. 305.) 



5 «, b. Views of the apex and base of two small casts. 



Fig. 6. 366. 2. Metoptojca? ruoosa. (Pag. 306.) 



6 a. Upper surface of the shell. 6 b. Lateral view. 6 c. Enlarged portion of the surface. 



Fig. 7. 239. 2. Caeinahopsis patelliformis. (Pag- 306.) 



7 a. A large individual of this species. 



7 b. Profile of the same. The elevation of the shell is less than usual, from compression. 



Fig. 8. 367. 3. Carinaeopsis oebiculatus. (Pag- 306.) 



8 a. View of a specimen, looking upon the apex. S b. Lateral view of specimen partially distorted. 



8 e. A portion of the surface enlarged. 



Fig. 9. 240. 1. Beixerophon bilobatus. (Pag- 307.) 



9 a. A large imperfect specimen. 



9 b, e. Lateral and profile view of a smaller specimen, showing the volutions eomprened. 



Fig. 10. 368. 4. Bellerophon cancellatus. (Pag- 307.) 



10 a. Lateral view of an entire individual. 



10 b. A portion of the surface enlarged, showing the cancellated striae. 

 10 r. A fragment of a shell, apparently of the same species. 



