PLATE 33. 
Fig. 1. 
173. 6. Atrypa extans. 
i a. Dorsal valve. 
Fig. 2 
Fig. 3. 
(Pag. 137.) 
(Pag. 138.) 
(Pag. 139.) 
3 a. Dorsal valve. 3 b. Ventral valve. 3 c. Cardinal view. 3 d. Enlarged profile view. 3 e. Front view. 
2 a. Ventral valve. 
174. 7. Atrypa nucleus. 
2 b. Dorsal valve. 
176. 9. Atrypa bisulcata. 
1 b. Ventral valve. 
2 c. Profile view. 
Fig. 4. 
177. 10. Atrypa deflecta. 
4 a. View of dorsal valve. 
4 b. Front view, showing the form of the two valves. 
(Pag. 140.) 
Fig. 5. 178. 11. Atrypa recurvirostra. (Pag. 140.) 
5 a. Dorsal valve. 5 b. Profile view. 5 c. Cardinal view. 5 d. Ventral valve separated from the dorsal. 
Fig. 6. 179. 12. Atrypa exigua. (Pag. 141.) 
6 a. Ventral valve. 6 b. Dorsal valve. 6 c. Cardinal view. 6 d. Dorsal valve of a small and large individual. 
Fig. 7. 181. 14. Atrypa circulus. 
7 a. Dorsal valve. 7 b. Cardinal view. 7 c. Profile view. 
(Pttg. 142.) 
Fig. 8, 9. 182. 15. Atrypa ambigua. (Pag* 143.) 
8 a & b. Usual form of the shell. 8 c. Front view in outline, showing two incipient plications in the sinus. 
9. Four valves represented precisely as they occur on the surface of a slab of limestone. 
Fig. 10. 183. 16. Atrypa hemiplicata. 
10 a. Dorsal valve of a specimen of the ordinary size. 10 b. Profile view. 
10 d. Dorsal valve and front view of a young specimen. 
10 e. Ventral valve of a large specimen. 10 f. Front view of the same. 
(Pag. 144.) 
10 c. Front view. 
Fig. 11. 184. 17. Atrypa (perhaps the young of A. extans). (Pag* 145.) 
11 a, b. Ventral and dorsal valves. 11c. Front view, the dorsal valve below. 11 d. Profile view. 
Fig. 12. 
12 a. Ventral valve. 
185. 18. Atrypa subtrigonalis. (Pag. 145.) 
12 b. Profile view. 12 c. Front, with the dorsal valve below. 
Fig. 13. 186. 19. Atrypa increbescens. (Pag* 146.) 
13 a, b. Ventral valve and front view. 13 l, in, n, o. Ventral valves and front views of two 
13 c, d. Ventral valve and profile view. larger individuals. 
13 e,f. Ventral valve and profile view of a more 13 p, r, s. Ventral valve, profile and front view of a 
gibbous form. larger specimen. 
. Front, profile, and ventral valve of a larger 13 t, u. Profile and front view of a gibbous specimen, 
and more rotund specimen. 13 w. Profile view of a very gibbous specimen, 
mall specimen of the western type. 13 x, y. Front and cardinal view of the same. 
13 g, 
13 k. 
Fig- 
14. 
14 a. 
Fig* 
15. 
The 
Fig* 
16. 
187. 20. Atrypa dentata. 
Dorsal valve. 14 b. Front view of the same, the dorsal valve below. 
180. 13. Atrypa modesta. 
wo upper figures are of the dorsal and ventral valve of a specimen ab( 
figure is of a small specimen, having the same characters. 
(Pag. 148.) 
14 c. Profile view. 
(Pag. 141.) 
188. 21. Atrypa sordida. 
(Pag. 148.) 
