PLATE LII. 
GrYROCERAS trivolye. 
Page 374. 
See Plate 52 A. 
Fig. 1. Ventral view of a nearly entire individual, showing the sinus in the ornaments of the test, and in the 
annulations of the internal mould. Upper Helderberg limestone. Schoharie, N. Y. 
Fig. 2. Dorsal view of the preceding. 
Fig. 3. Lateral view of the same, showing the number of volutions and the characters of the internal mould. 
Fig. 4. A portion of the outer volution of a larger individual, showing more distinctly the annulated character 
of the internal mould, with the rounded longitudinal ridges and strise of the crenulations. 
Schoharie, N. Y. 
Fig. 5. A longitudinal section preserving traces of the septa near the apex; but for the most part the internal 
characters have been destroyed. 
Fig. 6. A longitudinal section of a small fragment, showing the depth of the air-chambers and the concavity 
of the septa. Helderberg mountains. 
V 
