COPULATORY ORGANS OP THE AMNIOTA. 
37 
b. Hypothetical stage, intermediate between Crocodiles and Tortoises. An 
analogous, but dorsal, recessus uro-genitalis is developed in Lizards 
and Snakes. 
c. Chelonian stage. 
d. Hypothetical stage, intermediate between c and <?. 
e. Monotreme stage. 
f Marsupial stage. 
