PLATE evil 



Nautilus maqister. 



, Page 4*8. 



See Plates 62, 105, 108. 

 Figf. 1. The convex side of a septum of a large individual, showing the elliptical form with the broad sinus 



on the doi-sal side, and the siphuncle with the suiTounding areola. 

 Fig. 6. A fragment preserving the apical portions of the volutions, showing the fractured margins of the 



•ir-chambers from exfoliation, and the deep umbilicus. 

 Fig. 7. A fragment of one of the small inner volutions, showing the form and proportions of the sijihuncle, 



in its passage thi-ough the air-chambers, and its consti-iction at the septa. 

 Fig. 8. A longitudinal section of the smaller part of the outer volution, with a i)art of the inner volution, 



showing the depth of air-chambers, the form and pi-oportions of the siphuncle, etc. The figure 



is incomplete in the upper convex portion, the septa and chamber filling having been broken 



Avay, and the outline is not continued. The specimens are all from the Hamilton group. 



TowB of Hamburgh, Erie county, N. Y. 



Nautilus bucinum. 



Page 413. 

 See Plates 60, 106, 109. 

 Fig. 2. A fragment preserving four ur-chambers and the base of the grand chamber. 

 Fig. 3. A septum showing the foi-m of the transvei-se section and the position of the siphuncle. From 



the decomixising semi-calcareous shales of the Hamilton grouj), at Pratt's J''alls, Onondaga 



county, N. T. 

 Fig. 4. A fragment preserving a part of the chamber of habitation with several attached air-chambers. The 



test is partially preserved, and the fine cancellating stiiae are well defined. 

 Fig. 5. An enlargement of the surface of figure 4, showing the character of the surface-markings of the abell. 



From the shales of the Hamilton group on the eaut shore of Cayuga lake, N. T. 



I 



