PLATE 37. 
Page 
241 
1 a - y . Eatonia medialis. 
1 a.-b. Individuals in which the plications are more numerous than in ordinary specimens. 
1 c, d,f, g. Individuals in which the plications are much subdued, and in led are scarcely 
marked. 
1 e. An individual more extended on the beak than usual. 
1 li- o. Individuals presenting the usual varieties of form and surface of this species. 1'ig. 
1 o preserves the tine longitudinal striae. 
1 p. r, s. Ventral, front, and cardinal views of an unusually large individual, the valves of 
which are slightly opened. 
1 t, u. Ventral and dorsal views of the cast of a small individual. 
1 x, y. Casts of the ventral valve. 
2 a , b , c . Eatonia eminens. 
2 a. Dorsal valve of the cast. 
2 b. Ventral view of the same. 
2 c. Profile view, showing the great elevation of the dorsal valve. 
8 & 4. Rhynchonella eminens. 
3 a, b, c. Dorsal, front and profile views of an individual of medium size. 
4 a. Dorsal valve of a larger individual. 
