292 



GOM PHOCE HAS LUNATUM. 



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

 Vol. V.. Pt. II., p. 341, PI. 

 XCV.) 

 Distinguish inn; I 'hara 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 lunate; 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 striae. 



Found in the shales of the 

 Hamilton group, at Hamburg, 



Fig. 226. Gomphoceros manes, x ^ (after Erie CoUlltv, N. Y. (Hall.) 

 Hall). - ' 



Genus NAUTILUS. Breymus. 



[Ety. : Nautilos, sailor or navigator.] 

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



Shell with numerous volutions, coiled in a single plane, 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. (PI. XXVIII.) (Pal. N. Y., 

 Vol. V., Pt. II., p. 422, Pis. LXIL, CVIL, (Till. ) 



Distinguishing Characters— Large size; transverse and 

 ventro-dorsal diameter about as eleven to twelve: volutions 

 embracing to one-third the diameter of the inner contiguous 



