PLATE 15, 
Page 
Fig. 1. Orthis assimilis. 175 
1 a - d. Ventral, dorsal, profile, and front views of a small specimen. 
1 e. Cast of the ventral valve of a larger individual, showing the vascular and muscular im¬ 
pressions. 
LTISTRIATA. 176 
2 a, b, c. Dorsal, ventral and profile views of a very symmetrical specimen of medium size. 
2 d, e. Front and profile views of a larger individual. 
2/. Cardinal view. 
2 g, h. i. Dorsal, ventral, and profile views of a large individual. 
2 fc. Cast of ventral valve. 
2 l. Cast of dorsal valve of 2 k. 
2 in, n. Front and profile view of the preceding specimen. 
2 o, p. Casts of dorsal valves, showing muscular and vascular impressions. 
2 r. Cast of ventral valve of a full-grown individual. 
2 s, t. Front and profile view of the preceding. 
Ortiiis deformis. 
View of the dorsal valve and area of the ventral valve. 
Ventral valve of the same specimen, showing the contracted and distorted beak. 
174 
