PLATE ICYIIL 
Gyroceras spinosum. 
Page 382. 
See Plates 47, 48, 49, 99. 
Fig. 1. Ventral view of a fragment preserving its natural form, showing the characters of the sinus in the 
striae, and the rounded, revolving ridges on each side, formed by the rows of spines. Schoharie 
grit. Clarksville, N. Y. 
Fig. 2 id. Lateral view, showing one and remains of another revolving ridge, corresponding to the lateral 
rows of spines. 
Fig. 5. View of a gutta-percha mould, taken from the weathered lateral impression of a specimen, showing 
the frequency and prominence of the spines. Schoharie grit. Schoharie, N. Y. 
Fig. 6. An enlargement of the surface of a fragment, showing the undulating, lamellose lines of growth. 
Fig. 7. A fragment preserving its natural form, and retaining portions of the test adhering to the internal 
mould, showing the curvature and enlargement of the tube and the bases of the tubular expan¬ 
sions of the test. Schoharie grit. Schoharie, N. Y. 
CyRTOCRRAS 2EMULUM. 
Page 371. 
See Plate 97. 
Fig. 3. Lateral view of the specimen, with the apical portion imbedded in the surrounding matrix, showing 
the form and curvature of the tube and the lamellae of the test, which are seen extending into 
the surrounding rock. Upper Helderberg limestone. Pendleton, Ind. 
Fig. 4. Ventral view of the chamber of habitation of the preceding, showing the sinus in the aperture and 
ornaments of the test. The exfoliation of the test shows the interior filled with a deposit of 
crystalline material. 
