PLATE 30. 
Fig. 1. 
130. 
4. 
Lingula attenuata? 
(Pag. 94.) 
1 «, is the largest individual of 
this species yet seen. 1 b. A specimen of the ordinary 
size. 
Fig. 2 a, b, c. 
131. 
5. 
Lingula riciniformis. 
(Pag. 95.) 
Fig. 3 a, b. 
132. 
6. 
Lingula asqualis ( 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 striae 
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. 
Lingula elongata. 
Fig. 
6. 
135. 
9. 
Lingula curta. 
(Pag. 97.) 
(Pag. 97.) 
6 a. Specimen from the Utica slate. 
6 b. Specimen from the Trenton limestone. 
Fig. 7. 136. 10. Lingula obtusa. (Pag* 98.) 
7 a. A very perfect specimen of large size, giving the exact form of the shell : radiating strive scarcely visible. 
7 b. Another specimen, the form not quite so perfect as the last, but the radiating striae more distinctly visible. 
7 c. A smaller individual of the same species. 
Fig. 8. 137. 11. Lingula crassa. (Pag. 98.) 
8 a, b. View of both valves of this species. 
8 c. View of the edge of both valves, closed ; one being more convex than the other, and slightly arched. 
8 d. A larger specimen, somewhat crushed. S 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 b. A larger shell, less convex than the last : this portion is magnified. 
9 c Si, 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 lamellosa. (Pag. 99.) 
10 a. Ventral view. 10 b. Lateral view. 
Fig. 11. 
140. 4. Orbicula terminalis. 
(Pag. 100.) 
11 a. Dorsal valve, showing the central apex and lateral depression, which extends to the margin. 
11 b. Ventral valve with marginal apex. 11c. Lateral view of a perfect specimen. 
11 d. Ventral valve, marked with strong concentric lamellae; apex marginal. 
