22 
Explanation of Plate III. 
Conchidium decussatus Whiteaves. 
Figure 1-3. Ventral, lateral profile and dorsal views of a partially exfoli- 
ated specimen of small size. 
“ 4ft Ventral view of an exfoliated pedicle valve of a young individual 
showing the comparatively long median septum and very broad 
shell characterizing the ephibic stage of the species. 
“ 5. Dorsal view of an exfoliated fragmentary brachial valve of a young 
shell showing the comparative great breadth of the shell in 
early stages. 
“ 6. Lateral view of a pedicle valve showing the obsolescent character 
of the radiating plications in certain individuals. Note fine 
concentric striae. 
