Explanation of Plate II. 
Conckidium decussatus Whiteaves. 1 
Figure 1-2. Dorsal view and cardinal profile view of the type specimens 
after Whiteaves. 
“ 3. Umbonai profile view of natural cast of ventral valve showing 
the angular fold characterizing variety a. 
“ 4. Umbonai profile view of ventral valve of a natural cast showing 
cavity of spondylium and median septum and the median ridge 
characterizing var. a, but less angular than in Figure 3. 
“ 5. Umbonai profile view of a partially exfoliated pedicle valve showing 
regularly rounded transverse outline characteristic of var. b. 
“ 6. Ventral view of a partially exfoliated pedicle valve showing shallow 
sinus characteristic of var. c. 
1 All figures in this and succeeding plates are natural size. 
