NIAGARA FALLS AND VICINITY 1 85 



fined radiating" striae, which curve shghtly upward on the lateral 

 margins near the cardinal area; strongest striae reaching to beak; 

 increase by repeated intercalation; fine concentric striae. 



Found in great abundance in the Manlius limestone of North 

 Buffalo, etc., usually in the condition of molds. 



Genus chonetes Fischer de Waldheim 



[Ety. : xcoyrj^ funnel] 



(1837. Oryctographie du gouv. de Moscozu, pt 2, p. 134; 1892. 

 Pal. N. Y. V. 8, pt I, p. 303) 



Shells concavo-convex (in our species), with the pedicle valve 

 convex; hinge line straight, making the greatest diameter of the 

 shell; areas narrow; the triangular opening (delthyrium) in the area 

 of the pedicle valve covered by a convex deltidium. Upper margin 

 of area bears a single row of hollow spines. Area of brachial valve 

 without spines; cardinal process appearing quadrilobate. Interior 

 of shell strongly papillose in the pallial region. A low median ridge 

 divides the muscular area of the pedicle valve. A similar ridge oc- 

 curs in the brachial valve. External surface usually covered by 

 radiating striae. 



Chonetes cornutus (Hall) (Fig. 93) (1852. Pal. N. Y. 2:64, 

 pi. 21) ^ 



Distinguishing characters. Semi- \ \ [ ^ J J 



circular; fine equal striae, round, »^' ' :' m^m 



straight and bifurcating with similar 



interspaces ; three Cardmal spines on y^„ 93 chonetes cornutus natural size and 



each side of beak, obliquely diverg- 

 ing below, curving inward at middle and upper parts; outer one 



ngest. 



Found (doubtfully) in the Lockport limestone at Niagara. 



longest 



Genus orthis Dalman 



{sensii strictu) 

 i[Ety. : dpd6<i, straight; in allusion to hinge line] 



(1828. Kongl. Svenska Vet. Akad. Handl. p. 93, 96. Hall & 

 Clarke 1892; Pal. N. Y. v. 8, pt i, p. 192) 



Shells plano-convex in contour; costae strong, sharp and com- 

 paratively few, rarely if ever bifurcating; cardinal area of pedicle 



