PLATE 42. 
1 a - r . Atrypa reticularis. 
1 a, b, c, d. Ventral and profile views of young specimens. 
1 e. Dorsal view of the ordinary form of large individuals. 
If, g, h. Dorsal, front and profile views of a specimen from the Upper Pentamerus limestone. 
1 i, k, l. Dorsal, ventral and profile views of an elongate or ovoid form of this species. 
1 77?. Interior of the dorsal valve. 
1 n. Interior of the ventral valve, showing the teeth, muscular area, and the vascular im¬ 
pressions. 
1 o. The ventral valve of a smaller individual. 
1 p. A specimen with the. dorsal valve partially broken away, showing the internal spires, 
which, by mistake of the lithographer, are represented as one. 
1 r. Front view showing the arrangement of the spires. 
