PLATE 101. 
Eatonia pumila. 
1. The cast of the ventral valve, natural size. 
Fig. :> a - g . 
Eatonia peculiaris. 
43(3 
2 a, b, c. Dorsal, ventral, and profile views of a specimen, having the ordinary form and 
proportions of this species in the Oriskany sandstone. 
2 d. A cast of the dorsal valve of this species, showing the median septum and lateral 
lamellae. 
2 e. A east of the ventral valve, showing the form of the muscular impression, the median 
septum, and the small points of attachment for the adductor muscles. 
2 f. A specimen preserving a portion of the shell, which, on one side, is penetrated by the 
ramifying vessels. ( The lamcllose structure of the shell is confounded with the surface 
striae in the figure, which gives it an unnatural appearance.) Figure enlarged to one and 
a half diameters. 
2 g. A cast of the ventral valve, showing the muscular and vascular impressions ( See cor¬ 
rected figure on Plate ci \). 
Fig. 3 a - in . Merista lata. 431 
3 a. Ventral valve of a young specimen. 
3 b. Dorsal view of a large specimen. 
3 c, d, e. Profile, ventral, and front views of the same specimen. 
3 f. A ventral view of an intermediate form. 
3 g. k. Dorsal and ventral views of a cast of this species. ( The mark of the median septum 
is not shown in some of the figures.) 
3 i. Profile view of the same. 
3 fc. Ventral vhw of an imperfect cad, showing a larger muscular area. 
3 /. Ventral view of a large individual of this species. 
3 mi. Profile vie w of the sum -. 
