PLATE 93. 
Page 
Fig. 1 a - d . Chonetes complanata. 418 
1 a. An impression of the outside of the ventral valve of this species. 
1 6. A similar impression in sandstone, showing the concentric lines of growth. 
1 c. A cast of the interior of a ventral valve, showing the muscular impression and cavities of 
the dental lamella;. 
2 c (in centre of plate, by error for Id). An enlargement of the imprint of the surface, as 
sometimes seen in sandstone. 
Fig. 2 a , & 3 a , b . Stropiiodonta linckl^eni. 415 
2 a (the specimen referred with doubt to this species). The exterior of a ventral valve, in 
which the shell is partially exfoliated. 
3 a. The imprint made by the interior of the dorsal valve of a small individual, showing the 
cavities made by the bifurcating cardinal process, the impressions of the median crest, 
and the low ridges towards the centre of the shell. 
3 6. The impression of a larger ventral valve of this species, showing the same features as the 
preceding, the crenulated hinge-line, and the abruptly recurved outer margin. 
Fig. 2 b , c ? Stropiiodonta vascularia. 412 
2 6, c are referred to this species with some hesitation : they are the impressions of the ex¬ 
terior of the dorsal valve, and show the convexity corresponding to the concavity of the 
shell, which only occurs in an equal degree in this or the preceding species; the others in 
the rock being much less concave on the dorsal side. 
Fig. 4. Strophodonta magnifica. 414 
4. The cast of a ventral valve, preserving the marks of the muscular impression and the 
imprints of the radiating striae. 
