PLATE VI. 
Restoration of the ventral surface of Calymene senaria. 
4, 4. Thoracic legs. 
n, ^. Posterior pair of cephalic legs. 
Transverse section of the thorax of the same: s, dorsal shell; 4, intes- 
tinal canal; 7, leg; e, epipodite ; b, branchia. 
Transverse section of the thorax of Cerawrus plewrexanthemus, showing the 
position and character of the legs. The respiratory apparatus is not 
included. See description of the figure, ante, p. 224. 
Crustacean leg, as given by Eichwald. 
a. Natural size, 
b. Enlarged. 
Crustacean legs from the Hudson River formation, Cincinnati, Ohio, 
a. Leg with seven joints. 
b. Leg with six joints. 
