PLATE VI. 



Fig. 1. Restoration of the ventral surface of Cahjmene senaria. 

 4, 4. Thoracic U'gs. 

 n, n. Posterior pair of cephalic legs. 

 Fig. 2. Tmnsverse section of the thorax of the same : s, dorsal shell ; i, intes- 

 tinal canal ; I, leg ; e, epipodite ; b, branchia. 

 Fig. 3. Transverse section of the thorax of Ccraurus 2}leurcxanthemus, showing the 

 position and character of the legs. The respiratory apparatus is not 

 included. See description of the figure, ante, p. 224. 

 Fig. 4. Crustacean leg, as given by Eichwald. 



a. Natural size. 



b. Enlarged. 



Fig. 5. Crustacean legs from the Hudson River formation, Cincinnati, Ohio, 

 a. Leg with seven joints. 

 h. Leg with six joints. 



