280 



Found "in the Calcareous shales of the Hamilton group, 

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



pLEUROTOMAia.i lUGULATA. Hall. (Fig. 21 OA.) (ral. 

 N. Y., Vol. v., Pt. n., p. T.',, PL XX.) 

 Bist}iif>-uishin<>- Characters. — Low spire, rapidly expand- 

 ing volutions, the body-whoi'l foi-ming 

 almost the entire bulk of the shell; 

 broadly banded periphery; very convex 

 lower side, abruptly compressed to the 

 umbilical area; fine surface strifp. Fsu- 

 ally occurs as internal molds. 



Found in the Hamilton grou]) of 

 Eighteen ]\Iile Creek. (Coll. Am. Mus. 



Fig. 210 a. Pleurotoma 

 ria ruguluia lafter Hall). 



Nat. Hist. New York.) 



Genus BELLEROPHON. Montfort. 



[Ety. : Mythological name.] 

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



Shell symmetrically coiled in a single plane, with a flai-ing 

 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. 



Bellerophox patulus. Hall. (Fig. 211.) (Pal. X. Y., 

 Vol. v.. Pt. H., p. 100, Pis. XXH., XXIY.) 



Distinguishing- Clinracters. — Sub-globose, ventrico.se form ; 

 small umbilicus, closed before reaching 

 center; abru])tly and widely dilated 

 apertui-e, seiui-circular in outline; flat- 

 tened, broadly sinuate lip; reflexed inner 

 lip, Avhich extends over and partly 

 Fig. 211 BeUerophon covcrs the preceding volutions, forming 



patulus. Dorsal view, re- I o ' o 



duced (after Hair. .^ tliickeued pustulose "callus": con- 



centric strijp; strong concentric costa^ on the inrolled por- 

 tion of the shell. 



