PLATE LV. 



Gtrocekas Matheri. 



Page 377. 



Fig. 1. Front view of the internal mould of an individual, sbowing the character of the annulations on the 

 doi-sal side of the outer volution, and the sinus of the ornaments on the ventral side of the apical 

 portion. > 



Fig. 2. Lateral view of the preceding, showing the volutions and the enlargement of the tube. The annula- 

 tions and furrows of the crenulations are also shown. Upper Helderberg limestone, near Cat»- 

 kill, N. T. 



Fig. 3. Ventral view of a larger individual, showing the sinus of the annulations on the internal mould, and 

 the extension of the transverse lamellse into the surrounding matrix. Small fragments of the 

 test are preserved on a portion of the tube, showing the surface-markings. Schoharie, If. T. 



Rg. 4. Lateral view of the preceding, showing the curvature of the tube and the frequency of the annula- 

 tions. This specimen exhibits a common tendency of the last half of the outer volution to 

 become straight, and directed outward from the general curve of the spire. 



Fig. B. A fragment showing more closely coiled volutions. The larger extremity shows the concave surface 

 of a septum ; but the longitudinal section, as represented, preserves no evidences of the air- 

 chambers or siphuucle. Schoharie, N. T. 



Fig. 6. A septum showing the transveitse section of the tube. 



