PLATE 30. 



Fig. 1. 130. 4. LiNGULA ATTBNUATA? (Pag- 94.) 



1 <i, IS the largest individual ul' this species yet seen. I b. A Kpecimeii ul the oidiiiary size. 



Fig. 2 a, b, e, 131. 5. Linocla riciniformis. ' (Pag. 95.) 



Fig. 3 a, 6. 132. 6. Lihovl/l jE(iVAi4ia {a variety of the last species?). (Pag. 95.) 



Fig. 4. 133. 7. LiNGULA quadrata. (Pag- 96.) 



4 a. A specimen of the ordinary size ; the shell partially exfoliated, and presenting the strong radiating strise 



along the centre. 

 4 b. View of the edge of the shell, with the two valves closed. It appears slightly inequivalve from compression. 

 4 c. A specimen of larger dimensions, from which the shell is partially exfoliated. 



Fig. 5. 134. 8. LiNouLA elonoata. ( Pag. 97.) 



Fig. 6. 135. 9. LiNGULA curta. (Pag. 97.) 



6 a. Specimen from the Utica slate. G b. Specimen from the Trenton limestone. 



Fig. 7. 136. 10. LiNGDLA OBTUSA. (Pag. 98.) 



7 a. A very perfect specimen of large size, giving the exact form of the shell : radiating striee scarcely visible. 

 7 b. Another specimen, the form not quite so perfect as the last, but the radiating stris more distinctly visible. 



7 c. A smaller individual of the same species. 



Fig. 8. 137. 11. LiNGULA CHA88A. ( Pag. 98.) 



8 a, b. View of both valves of this species. 



8 e. View of the edge of both valves, closed ; one being more convex than the other, and slightly arched. 

 fs d. A larger specimen, somewhat crushed. 8 e. A smaller specimen. 



Fig. 9. 138. 2. Orbicula? FiLosA. (Pag. 99.) 



9 a. A young shell, very convex or obtusely conical in form. 



9 t. A larger shell, less convex than the last : this portion is magnified. 



9 e It d. Two apparently full grown shells of this species; the form is much depressed, nearly flat, and the 

 surface completely covered by fine striae. 



Fig. 10. 139. 3. Orbicula lakellosa. (Pag* 99.) 



lU a. Ventral view. 10 b. Lateral view. 



Fig. 11. 140. 4. Orbicula tbrminalu. (Pag. 100.) 



tl a. Dorsal valve, showing the central apex and lateral depression, which extends to the margin. 

 1 1 b. Ventral valve with marginal apex. 1 1 c. Lateral view of a perfect specimen. 



11 d. Ventral valve, marked with strong concentric lamellae; apex marginal. 



