PLATE 37. 



Fig. I a - y. Eatonia medialis. 241 



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 1 c rf are scarcely 

 marked. 



1 c. An individual more extended on the beak than usual. 



1 A - 0. Individuals presenting the usual varieties of form and surface of this .species. Fig. 

 1 o preserves the fine longitudinal stria;. 



1 p, r, «. 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. 



Fig. 2 a, b, c. Eatonia e.minens. 242 



2 a. Dorsal valve of the cast. 

 2 b. Ventral view of the same. 



2 c. Profile view, showing the great elevation of tlic dorsal valve. 



Fig. 3 & 4. Rhynchonella e.minen.s. 237 



3 a, b, c. Dorsal, front and profile views of an individual of medium size. 



4 a. Dorsal valve of a larger individual. 



