292 



G ( ) M P H () ( ■ E K A S UNA Tl M . 



Hall. (Fig. 227.) (Pal. X.Y., 

 \o\. v., Pt. II., p. :\U, PI. 

 X(T.) 



Distinguishing ( 'hn rn cters. — 

 Large size; regularly arcuate 

 form; broadly oval cross- 

 section, the lateral diameter 

 longest; one side (dorsal) is 

 concave, and the others are 

 convex, the longitudinal sec- 

 tion being Innate; large liv- 

 ing chamber, with the great- 

 est expansion anterior to the 

 last septum; siphuncle ex- 

 panded between the septa; 

 lamellose lines of growth, and 

 distinct longitudinal sti'irp. 



Found in the shales of the 

 Hamilton group, at Hamburg, 

 (after Erie Conntv, N. Y. (Hall.) 



Genus NAUTILUS. Breynius. 



[Ety. : Nautilos, sailor or navigator.] 

 (1732: Dissert. Polytli., p. 11.) 



Shell with numerous volutions, coiled in a single ])hnie,the 

 volutions contiguous, the later ones indented by the preced- 

 ing ones. The septa are simple, concave upwards, with 

 simple, arched or waved sutures. Siphuncle central or sub- 

 central; lips sinuous; surface smooth or variously orna- 

 mented. 



Nautilus MAGiSTER. Hall. (PL XXVIII.) (Pal. N. Y., 

 Vol. v., Pt. IL, p. 422, Pis. LXIL, CVIL, CVIII.) 



Distinguishing (haracters. — Large size; transverse and 

 A'entro-dorsal diameter about as eleven to twelve: volutions 

 embracino- to one-third the diameter of the inner conti<iuous 



