PLATE 24. 
Fig. 1. 464. 35. Atrypa naviformis. (Pag. 76.) 
1 a. View showing the ventral valve, with the elevated beak of the dorsal valve. 
1 b. View of the dorsal valve of a full grown shell. 
1 c, d. Front and cardinal view of the same shell. 
1 e. Profile view of the same. 1 /. A portion of the surface enlarged. 
1 g, h, i, k. Several views of a young shell, the front 1 i showing a scarcely formed sinus, contrasting in 
this respect very strongly with fig. 1 c. 
Fig. 2. 465. 36. Atrypa cylindrica. (Pag. 76.) 
2 a. View of the ventral valve, showing the beak of the dorsal valve elevated above it. 
2 b. Dorsal valve of the same. 2 c. Profile view of the same. 
2 d, e, f. Ventral, dorsal and profile views of a smaller shell. 
2 g. Cardinal view of the last. 2 h. Front view of the same. 
Fig. 3, 4. 466. 37. Atrypa intermedia. (Pag. 77.) 
3 a. View of the ventral valve. 3 b. Profile of the same. 3 c. Cardinal view. 
3 d. Front view, showing the scarcely sinuous margins. 
3 e. A specimen with the shell partially removed, showing three strong elevated lines in the cast. 
3 /. A cast of this species. 
4 a, b, c, d. Ventral, profile, cardinal, and front views of a young shell, apparently of the same species. 
Fig. 5. 
467. 
38. 
Atrypa -(cast). 
(Pag. 78.) 
5 a. 
Cast of dorsal valve. 
5 b. Profile of the same. 
Fig. 6. 
468. 
39. 
Atrypa cylindrica? (cast). 
(Pag. 78.) 
6 a. 
Dorsal view of cast. 
6 b. Profile of the same. 
Fig. 7. 
471. 
2. 
PeNTAMERUS FORNICATUS. 
(Pag. 81.) 
7 a. Ventral valve, with the large elevated beak of the dorsal valve incurved over it. 
7 b. Dorsal view of the same specimen. 
7 c. Cardinal view, showing the great convexity of the dorsal valve. 
7 d. Profile view of the same. 
