PLATE 101 A. 
Page 
1 a - h. Eatonia peculiaris. 436 
1 a. Interior of the ventral valve, showing the form of the muscular impressions, teeth, etc. 
1 b. Profile of the same, showing the little elevations of the shell-surface, and the small pits 
for the adductor muscles a and the teeth t. 
1 c. The dorsal valve, showing the crural processes and muscular impression. 
1 d. Front view of the same, showing the deep sinus, and the relation of the crural processes 
and median septum. 
1 e. Section of the dorsal valve, showing the elevation of the median septum and the crural 
processes. 
1 f. Figure of the ventral valve (the inflected extension in front being removed ) with a part 
of the dorsal valve attached, showing the crural processes, the median septum of the 
dorsal valve, the adductor imprints, the small oblique pits penetrating beneath the 
lamina} of the shell, and the cardinal muscular impression. 
1 g. View of another specimen with the dorsal valve downwards and the ventral valve broken 
away, to show the median septum articulating with the bifurcating cardinal process of 
the dorsal valve. 
1 h. A cast of the ventral valve, showing the muscular and vascular impressions. This and 
the preceding figure are enlarged to once and a half the natural size. 
2 a , b. Eatonia whitfieldi. 437 
2 a. The exterior of the ventral valve. 
2 b. The interior of the ventral valve, with the apex of the dorsal valve attached. 
3-6. Eatonia sinuata. 438 
3 a. Dorsal view of a large individual, which shows the prevailing form. 
3 b, c. Profile and front views of the same. 
4. Dorsal view of a more orbicular form. 
5. Ventral view of a cast, showing the strong muscular impression with the small central 
adductor impression. 
6. Ventral view of a cast preserving a part of the shell; the form of the shell and muscular 
impression more rotund than the preceding. 
7 & 8. Riiynciionella ramsayi. 446 
7. View of the dorsal side of the specimen. 
8 a, b. Ventral and dorsal views of the cast of this specie r. 
