'• 



PLATE 79. 



Fig. 1. 133. 7. LiNouLA QUADRATA. (Pag. 286.) 



Figures of two specimens, showing the difTereuce ordinarily seen in the form of this fossil. • 



if the surface magnified. 



1 c. A portion of the surface magnified. 



Fig. 2 



141. 4. Leptjena altesnata. 



(Pag. 286.) 



•2 a. Mould of the interior of the convex valve of tliis species, showing the form of the visceral impression, 



the oblique teeth, etc. The nasute character is well preserved. 

 ■i b. Figure of a similar specimen, where the nasute character is less conspicuous. 

 2 e. A smaller specimen of the same character, showing a slight contraction in front, 

 a d. A portion of the surface of one of these enlarged, showing the striato-punctate character. 

 2/". The impression made by the outside of the convex valve of this species, showing the fascicles of striae in 



a perfect manner. 

 2/**. A cast of a large symmetrical specimen, showing the same characters of the surface, form of visceral 



impression, etc. 

 2 g. A small specimen, preserving the shell, and showing the strix in interrupted fascicles. 

 2 g\. A portion of the surface enlarged. 

 2 3j, t. Figures of specimens which still preserve a part of the shell, having the stria: in broad fascicles of 



small ones separated by larger ones. 

 2 k. Interior of the ventral valve, showing two small teeth on the hinge line, with three diverging callosities. 

 2 /. Mould of the interior of the ventral valve, showing the two cavities made by the teeth, and the impressions 



of the radiating callosities. 



^ 



'♦ 



Fig. 3. 146. 9. Lept^na sericea. 



3 a. A mould of the interior ef the shell. 



3 6. An enlarged portion, showing the striato-punctate character of the surface. 

 3 a*. Another specimen, presenting more distinctly the usual character of casts of this species. 



(Pag. 287.) 



Fig. 4. 155. 2. Orthis testddinabia. (Pag. 288.) 



4 a, b. Casts of the interior of the dorsal valve. 1 c. Cast of the interior of the ventral valve. 



4 d. A similar cast, more strongly impressed by the striae. 



4 e. A fragment of the impression of the outer side of the ventral valve, showing the fine concentric striie, 

 which crenulate the diverging strise. 



Fig. 6. 341. 19. Orthis erratica. 



8 a, b. Dorsal and ventral views of the cast of a large specimen. 



5 e. Front view of a larger specimen. 



5/. Profile view of a moderately convex specimen. 



(Pag. 288.) 

 5 d. Ventral view of a small specimen. 

 5 e. Cardinal view of a large specimen. 



Fig. 6: 342. 20, 



5 a*. A specimen, natural size. 



S c*. Several striae enlarged, showing the bifid and trifid character. 



Oethis centbilineata. (Pag. 289.) "*" ^ 



5 b*. Magnified portion of the cardinal line and visceral impression. '' '^'^ 



Fig. 6. 



186. 19. Atryfa increbescens. 



Fig. 7. 343. 5. Orbichla? subtruncata. 



7 a. A small fragment with several individuals ugion the surface. 



Fig. 8 a. 



Fig. 9. 



344. 6. Orbicula? crassa. 



345. 7. Orbicula cjelata. 



(Pag. 289.) 



(Pag. 290.) 



7 ft. A single specimen enlarged. 



(Pag. 290.) 

 (Pag. 290.) 



9 a. An imperfect specimen. b. The same enlarged, to show the central depression and lateral plications. 

 9 e. A portion of the surface still farther enlarged, showing the character and arrangement of the papillae. 



