280 



Found "'in the Calcareous shales of the Hamilton group, 

 at Hamburg, ou the Shore of Lake Erie." ( Hall. ) 



Pleurotomaria rugulata. Hall. (Fig. 210A.) (Pal. 

 N. V.. Vol. V.. Pt.II.,p. 75, PI. XX.) 



Distinguishing Characters. — Low spire, rapidly expand- 

 ing volutions, the body-whorl forming 

 almost the entire bulk of the shell; 

 broadly banded periphery; very convex 

 lower side, abruptly compressed to the 

 umbilical area ; fine surface stria'. Usu- 

 ally occurs as internal molds. 



Found in the Hamilton group of 

 Eighteen Mile Creek. (Coll. Am. Mus. 



Fig. 210A. Pleurotoma 

 ria rugulata (after Halh. 



Nat. Hist. Xew York.) 



Genus BELLEROPHON. Montfort. 



[Ety. : Mythological name.] 

 (1808: Conch. Syst, Vol. I., p. 50.) 



Shell symmetrically coiled in a single plane, with a flaring- 

 mouth, which bears a notch or sinus in the center of the 

 outer lip. This notch is continued backwards in a revolving 

 band, of varying strength, while the concentric growth-lines 

 make a sharp reentrant. The inner lip is thickened and ex- 

 panded on the inrolled spire. 



Bellerophon patulus. Hall. (Fig. 211.) (Pal. N. Y., 

 Vol. V.. Pt. II., p. 100, Pis. XXII., XXIV.) 



Distinguishing Characters. — Sub-globose, ventricose form ; 



small umbilicus, closed before reaching 

 center; abruptly and widely dilated 

 aperture, semi-circular in outline: flat- 

 tened, broadly sinuate lip; reflexed inner 

 lip, which extends over and partly 

 covers the preceding volutions, forming 

 ;i thickened pustulose "callus*': con- 

 centric striae; strong concentric costse on the inrolled por- 

 tion of the shell. 



I'n. '.'i! Bellerophon 

 natulus I 'orsal \ iew . re 



duced '.ill. -I- Hall . 



