PLATE XCVIII. 



GtROCERAB 8PIN0SUM. 



Page 8*8. 



See Plates 47, 48, 49, 99. 



Pig. 1. Ventral view of a fragment preserving its natural form, eliowing the charactera of the sinus in the 



stria;, and the roundeil, revolving ri<lg«8 on each side, formed by the rows of spines. Schoharie 



grit. ClarksvUle, N. T. 



Fig. 2 id. Lateral view, showing one and remains of another revolving ridge, coiTesponding to the lateral 



rows of spines. 

 Fig. 6. View of a gutta-percha mould, taken fi-om the weathered lateral impi-ession of a specimen, showing 



the frequency and prominence of the spines. Schoharie giit. Schoharie, N. T. 

 Fig. 6. An enlargement of the surface of a fragment, showing the undulating, lamellose lines of growth. 

 Pig. 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. 



CyRTOCERAS .ffiMDLUM. 

 Fa«e371. 

 See Plate 97. 

 Fig. 8. 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. Upjier Helderbei-g 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. 



