PLATE CII1. 
Gyroceras Cyclops. 
Page 387. 
See Plates 101, 102, 104. 
Fig. 1. A fragment, showing the transverse section of the tube and one of the foliate expansions of the test, 
with its surface-markings and the strong plications of the margin, which are more subdued at 
the base and along the walls of the tube. Upper Helderberg limestone. Columbus, Ohio. 
Fig. 2 id. Lateral view, showing the surface-markings on the tube and the inclination and extension of the 
transverse expansions. 
Gyroceras Eryx. 
Page 3S6. 
See Plate 58. 
Fig. 8. Lateral view of a large individual, showing the size and curvature of the shell. Some of the septa 
are preserved, and show the regular depth of the air-chambers and the straight septal sutures 
at light angles to the spiral axis of the tube. Magnesian limestones of the Hamilton group. 
Near Milwaukee, Wis. 
Gyroceras, sp. indet. 
Fig. 4. A fragment found in the same association with G. Eryx, but of undetermined specific relations. 
The figure is a ventral view, and shows traces of the siphuncle exposed in the process of 
weathering. Magnesian limestones of the Hamilton group. Near Milwaukee, Wis. 
