PLATE 22. 
1. 172. 1. Spirifer biforatits, var . lynx. { Pag. 65.) 
1 a. Ventral valve, with a very short hinge-line. There are four mesial plates, and twelve or thirteen on each 
side. 
1 b. The ventral valve of another specimen, having the mesial lobe worn smooth, and ten ribs on each side. 
1 c. The dorsal valve of a large specimen, having four ribs in the mesial sinus, and ten on each side. 
1 d. The interior of the dorsal valve, showing the fbrm of the muscular impression, and the papillose surface 
on each side. 
1 e. Cardinal view of the ventral valve, showing the projecting dental processes. 
2. 452. 3. Spirifer radiatus. (Pag. 66.) 
2 a. Ventral view of a specimen having the cardinal extremities somewhat contracted, and the dorsal area 
very wide and fully exposed. 
2 b. Profile view of the same. 
2 c. A specimen with the dorsal extremities more extended, and the area broad. 
2 d. An individual much extended in width, having the cardinal extremities rounded and the area almost 
closed. 2 e. A similar specimen, larger than the last. 
2 /. A specimen with the hinge-line very much contracted and the angles rounded, with the area nearly 
closed. 
2 / f- A portion of the surface enlarged, showing the character of the striae. 
2 g. A specimen which has apparently suffered no pressure. The beaks are approximate, the dorsal one 
much curved, and the area nearly closed. The cardinal extremities are rounded, and the whole con¬ 
tour of^fihe shell very round. 2 h. Profile view of the last. 
2 i. Front view of the same, showing the elevation of the mesial lobe. 
2 fc. Ventral view of a larger specimen with the cardinal extremities rounded, the beak much elevated and 
incurved, and the area very small. 2 l. Profile view of the last. 
2 m. Dorsal view of the same. 2 n. Front view of the same. 
2 o. Dorsal view of a larger specimen, having the extremities rounded, and the beak much elevated and in¬ 
curved. 
2 p. Ventral view of the same, showing the area nearly closed. 
2 r. Cardinal view of the same shell. 
2 s. Dorsal view of a specimen with the shell partially exfoliated, showing the direction of the dental plates. 
2 t. Dorsal area of a single valve, showing the narrow foramen. 
3- 451. 2. 
Spirifer-. 
(Pag. 66.) 
