PLATE 28. 
Page 
Fig. la-/. Spirifer modestus. 203 
1 a. Dorsal view of a specimen of ordinary size. 
1 b, c, d. Ventral, dorsal and profile views of a larger individual. 
1 e. The interior of the ventral valve. 
1 f. Front view of 1 a. 
Fig. 2 a - f. Spirifer saffordi. 203 
2 a, b, c. Dorsal, ventral, and profile views of the same specimen. 
2 e. Front view of the same. 
2/. Enlargement of the surface. 
Fig. 3 a - d . Spirifer tenuistriatus. 204 
3 a, b, c. Ventral, dorsal, and profile views. 
3 d. Enlargement of the surface strife. 
Fig. 4 a - e . Spirifer octocostatus. 205 
4 a, b, c. Ventral, dorsal, and profile views. 
4 a f, b f, c f. Ventral, dorsal, and profile views of other specimens. 
4 d. Cardinal view of 4 c t 5 showing the foramen. 
4 e. Interior of the ventral valve. 
Fig. 7. Spirifer concinnus. 200 
7 a, b. Dorsal and ventral views of a large specimen from the Upper Pentamerus limestone. 
Fig. 8 a - d. Spirifer macropleurus. 202 
8 a, b, c. Casts of the ventral valve, showing some variety in the forms of the muscular im¬ 
pressions. 
8 d. Enlargement of the surface striae, taken from an impression of the exterior in the shaly 
limestone where the shell has decomposed. The concentric striae are rarely preserved on 
the surface of the shell. 
