PLATE CXXVI. 



Nautilus Hyatti. 



Page 37. 

 Fig. 1. Dorsal view of a plaster cast, taken from the natural mould, showing- the form of the tube, and the 

 well-preserved surface ornamentation. 



Hamilton group. Cumberland, Maryland. 



Nautilus oriens. 



Page 37. 

 Fig. 2. Longitudinal section of the individual figured on plate 106, Pal. N. Y., vol. v, pt. ii, showing the 

 capacity of the grand chamber, the septa, and remains of the moniliform siphuncle. The inner 

 volution has been filled with calcite, and the septa removed, but a portion of the beaded siph- 

 uncular tube remains in situ. 



Hamilton shales. Richmond-mile, Schoharie county. 



Nautilus pakallelus. 



Page 38. 



Fig. 3. Ventral view of the specimen, showing the gradual enlargement of the tube and the parallel re- 

 volving ridges of the test. 



Fig. 4. Id. Lateral view, showing the curvature of the tube, the angular periphery, and the concavity of 

 the last septum. The parallel revolving ridges are seen to be less frequent than on the ventral 

 side. 



Fig. 5. Id. The last septum, as preserved in the specimen, showing the subcentral position of the siph- 

 uncle, and the lenticular transverse section of the tube. The dorsal side is more convex than 

 the ventral, and the carinations of the lateral angles are directed upward and outward, 

 Coal measures ? Ohio ? 



Nautilus (Discites) Marcellensis. 



Page 39. 

 Fig. 6. Dorsal view of a well-preserved individual, illustrating the essential features of this species. The 

 variation in the enlargement of the dorsal, ventral and lateral sides is well contrasted. The 

 dorso-lateral margin is continuous and slightly reflected, while the ventral angles are marked 

 by a row of nodes. A single revolving line over the siphuncle indicates its position and that of 

 the ventral side. Four segments of the siphuncle are exposed, showing its concavesides within 

 the cavities of the air-chambers. A portion of the test is adhering to the ventrum, preserving 

 the cancellate ornaments and the broad sinus of the concentric striae over this side of the tube. 

 Goniatite limestone. Manlius, Onondaga county. 



Gyroceras Stebos. 



Page 36. 

 Fig. 7. Lateral view, showing the enrollment of the tube and the strong elevated nodes ornamenting the 

 lateral angles. Traces of the transverse stria? are preserved near the aperture. 

 Waverly group. Warren, Pennsylvania. 



