PLATE 17. 



Page 



Fig. 1 & 2. Stkophomena woolworthana. 192 



1 a. Ventral valve of an individual of medium size. 



1 h. Dorsal valve of a larger individual, showing the area of the opposite valve and the closed 

 foramen. 



1 c. Ventral valve of the same. 



1 d. Profile view of the same. 



1 c. Ventral valve of a large individual. 



1 /. View of area of 1 e. 



1 g. Cardinal view of an entire individual, showing the area of the ventral valve, and the 

 convexity of the dorsal valve. 



1 A, i, fc, I. Interior of the ventral valves of several individuals of different size, and showing 

 some variety in form of the muscular impressions. 



1 m. A cast of the ventral valve. 



1 n, 0. Interior of dorsal valves, sliowing the cardinal processes, with some difference in the 

 strengtli of the muscular impressions and proportional length of the hinge-line. 



1 p, r. Cardinal view of ventral valve, showing the cardinal processes and the same enlarged. 



1 », (. Enlargement and profile of the striae. 



2 a, b, e. Casts of the interior of the dorsal valves of several individuals. 



