Figs. 1- 
Fig. 5. 
Fig. 6. 
Fig. 7. 
Fig. 8. 
PLATE V. 
4. Longitudinal sections of Calymene senaria. Enlarged to three diameters. 
s. Dorsal shell. 
c. Cephalie cavity. 
4, 4. Oblique sections of the legs. 
v. m. Median lobe of the ventral membrane. 
Lateral view of an enrolled specimen of the same species, 
a, à. Line of section, Fig. 3, Plate III. 
b, b. Line of sections, Figs. 6-10, Plate I. 
Anterior view of the same. 
a, ๕. Line of the section, Fig. 1, Plate V. 
b, b. Line of the section, Fig. 3, Plate V. 
c, c. Line of the section, Fig. 2, Plate V. 
0, 0. Line of the section, Fig. 4, Plate V. 
Ventral view of a young Limulus polyphemus. 
Ventral view of the head of Eurypterus nemipes. 
