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 IV. Enlargement of surface where the edges of the lamellse are ornamented with little gra- 

 nules, giving the appearance in profile as represented in 1 a:. 



1 y. The surface where the granules are worn off, and the lamellse 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 TTpper Pentamerus limestone. 



