296 PALEONTOLOGY OF NEW YORK. 



which are fiisciculose on the anterior portion of the shell, lladiiiting striae 

 are obscurely visible on botli the specimens figured. On the UTubonal ridge 

 the test is raised into a thin crest. Interior unknown. 



The principal specimen described has a length of 80 mm., and a height of 

 about 28 mm. 



This species resembles G. Hamillonensis, but differs in having the becaks nearer 

 to the anterior end, in its more elongate form, and in the radiating strias of the 

 surface-characters not observed in specimens referred to that species. As com- 

 pared with G. truncata, it is a more elongate shell with a proportionally longer 

 and less oblique hinge-line. 



Formation and locality. In the soft shales of the Hamilton group, on the 

 shores of Canandaigua lake, N. Y. 



GONIOPHORA HaMILTONENSIS. 



PLATE XLIII, FIGS. 8-15, 17-21. 



Sanguinoliles HamiWinensiii, Hall. Pi-elim. Notice Lamellibrancliiata, 2, p. 36. 1870. 

 Oim'wpliora Haviiltoieiisig, Hall. S. A. Miller. Cat. Amer. Pal. Foss., p. 192. 1877. 



" " " Pal. N. Y., vol. V, pt, 1. Plates and Explanations: PI. 43, figa. 8-21. 



1883. 



Shell large, trapezoidal ; length more than twice the height ; basal margin 

 gently curving, sometimes nearly straight and slightly affected by the sinus. 

 Posterior margin obliquely truncate. Anterior margin concave below the 

 beak and abruptly rounded below. Cardinal line very slightly arcuate, 

 extending for two-thirds the length of the shell ; margins inflected, forming 

 a long, deep escutcheon. 



Valves moderately convex below the umbonal ridge, and concave above it 

 to the cardinal line. 



Beaks sub-anterior, small, clo.sely incurved, situated from one-fourth to 

 one-sixth the length of the shell from the anterior margin. Umbonal ridge 

 angular, strongly defined, arching over the beaks and extending in nearly a 

 direct line to the post-basal extremity. Umbonal region scarcely gibbous, 

 separated from the anterior end by a broad undefined sinus, which becomes 

 obsolete in some specimens, owing to compression. 



