PLATE 91. 
Page 
Fig. 1, 2, 3. Ortiiis musculosa. 0 409 
1 a, b. Dorsal and ventral views of a cast of a small individual. 
2 a. Ventral view of a larger individual, with a small muscular impression. 
2 b, c. Cardinal and dorsal views of the preceding, showing the cavities made by the brachial 
lamellae and cardinal process, and the impression of the longitudinal crest. 
3. The ventral side of a cast with narrow and small muscular impressions (perhaps a distinct 
species). 
3 a. The cast of a specimen preserving a large and strongly marked muscular impression. 
3 b. A mould from the cast shown in the preceding figure. ( The imprints of the adductor 
muscles are omitted in the drawing.) 
3 c, d, e. Dorsal, profile and cardinal views of the same specimen. 
Fig. 4 & 5. Orthis hipparionyx. 407 
4. The cardinal area, showing the closed foramen. 
5. A portion of the surface of a young shell enlarged, showing the character and direction of 
the striae. 
