PLATE 4 (bis). 
Fig. 1. 391. 17. Modiolopsis orthonota. (Pag. 10.) 
1 a . Eight valve of a small specimen, with the posterior extremity rounded and the anterior one extended. 
1 b. Right valve of' a larger specimen, having the anterior extremity less prolonged. 
1 c. Yiew of the hinge-line and cardinal area of the last. 
Fig. 2. 392. 18. Modiolopsis? primigenius. (Pag. 11.) 
2 a . A small specimen, with the beak very prominent, and almost vertically truncated at the posterior, ex¬ 
tremity. 
2 b . A cast having the markings almost entirely obliterated, and showing a fold or depression along the 
hinge-line. 
2 c. A specimen partially preserving the shell, which is alated on the posterior dorsal margin, and slightly 
acute in front. 
2 d. A fragment preserving an impression of the shell, showing the concentric and radiating lines. 
2 e. A portion of the same enlarged. 
Fig. 3. 393. 19. Pleurotomaria? pervetttsta. (Pag. 12.) 
8 a . Profile view of a specimen. 3 b . Yiew of the base. 3 c. Yiew of the apex. 
3 d . A fragment of the sandstone containing numerous individuals of this species, with Bucania trilobata . 
Fig. 4. 
394. 
20. 
Pleurotomaria litorea. 
(Pag. 12.) 
4 a 
. Profile view of specimen. 
4 b . Yiew of the apex. 
Fig. 5 . 
396. 
7. 
Bucania trilobatus. 
(Pag. 13.) 
5 a 
. Side view of a specimen. 
5 b . Dorsal view of the same. 
3 d . The upper figure in this specimen, and.the lower lefthand figure, are of this species. * 
Fig. 6. 397. 2. Oncoceras gibbosum. (Pag. 13.) 
6 a . Yentral view of the specimen. 6 b . Lateral view. 6 c . Section of same. 
Fig. 7. 398. 26. Orthoceras -. ( Pag. 14.) 
7 a. Lateral view of the fragment. 7 b. Section showing position of siphuncle. 
Fig. 8. 399. 27. Orthoceras multiseptum. |Pag. 14.) 
8 a. A fragment of a small specimen, showing a part of the outer chamber. 
8 b. A fragment of a larger specimen, showing the commencement of the outer chamber, with a narrow one 
at the termination of the others. 
