VlM CIX. 



Nadtilus bdcinum. 



Vage 412. 

 See Plates 60, lOfi, 107. 

 Tig. 1. A venira! view of the grand chamber of a young sliell, iireaerving' the surface oraamentation in a 

 remarkable <legi-ee of pei-fection. The sharp, elevated, revolving sti-iffi, with finer intermediate 

 ti-ansvei-se stritp, are precisely of the character of those on the surface of the specimen of this 

 species from the Gonialite limestone, plate 60, figs. 1-3. 



Tliis surface-marking re8Cml)le8 that of the specimen referi-ed to N. liratus, var. juvenis, 

 figs. 5 and (5, pi. 50, but the revolving strijc are more closely arranged and less conspicuous on 

 the concave side, while the tube is free fwm any transvei-se undulations which mark that 

 variety. West shore of Canaiidaiffua lake, N. ¥. 



Fig. 2. A fragment pi-eserving the chamber of habitation nearly entire and two attached air-chambers. The 

 surface is marked by the undulating slrite of growth and very fine revolving stiiie. On the 

 concave side of the specimen the i-evolving strife are al)out one mm. distant from each other; 

 and (m the convex side thei-e are stronger strise of about the same or a greater <listance apart, 

 between which are finer striae. From the ai-enaoeous shales of the Hamilton group. Near 

 Casenovia, N. ¥. 



Fig. ^6. An enlargement from the dorso-lateral surface of a specimen of this species, showing the distant 

 revolving strise and the finer concentric striae. Fi'om the dark, coloreti shales. Shore of Cayuga 

 Lake, X. Y. 



Nautilus acr.sus. 



Page 417. 

 Fig. 3. The ventral side of the chamber of habitation, showing the form (which is slightly compressed), and 



the tine equal striiE of the surface. 

 Fig. 4. The concave doi'sal side, showing the form of the transverse section, the position of the siphuncle, 



and the fine surface-markings. There is a slight indentation near the uppei' fractured edge of 



the shell, which has apparently been produced by the contact of the inner volution. 

 Fig. 5. An enlargement of the surface, showing the fine, nearly equal strife, of which there ar^ from twelve 



to fifteen in the space of five mm. In the arenaceous thales of the Hamilton group. Pla'mfield, 



Otsego cotinty, N. T. 



GONIATITES VaNUXEMI, 



Pago 434. 



See Plates 66, 67, 68, 69, 74, 109. 



Fig. 7. A transveife section of the disc, showing the fonu of the inner volutions, their gradually increasing 



dorso-ventral diameter, and final form in the grand chamber near the aperture. 

 Fig. 8. A portion of the periphery of a large individual of the species, showing the deep sinuosity in the 

 striae, and their great thickness and imbricating character upon the angles of the periphery. 

 From the Goniatite limestone. Manllus, N. T. 



Nautilus (Discites) Marcellensis. 



Pa^ 4-2S. 

 See Plate 65. 

 Fjg. 9. A »mall individual of this species, which is principally a cast of the interior, pi-eserving the shell 

 ufHin a part of the grand chaml>er, which should have been represented as broken along the 

 peripheral angle. Uanlius, N. Y. 



