PLATE 25. 
Page 
Fig. 1 a - z. Spirifer cyclopterus. 199 
1 a - s. Figures of several individuals, showing gradations in size, modifications of form, etc. 
. 1 u. Interiors of ventral valves. 
1 w. Enlargement of surface where the edges of the lamellae are ornamented with little gra¬ 
nules, giving the appearance in profile as represented in 1 x. 
1 y. The surface where the granules are worn off, and the lamellae are seen to be finely striated. 
1 z. Profile of the imbricating concentric striae. 
Fig. 2 a - i. Spirifer concinnus. 200 
2 a - e. Views of a single large specimen from the shaly limestone. 
2/. Enlargement of the surface. 
2 g, h, i. Ventral and front views of specimens from the Upper Pentamerus limestone. 
