302 PALAEONTOLOGY OF NEW YORK. 



Beaks situated less than one-third the length of the shell from the anterior 

 end, closely incurved. Umbo prominent. Umbonal slope distinctly carinated 

 and terminating at the basal extremity. 



Test of moderate thickness, marked by fine undulating concentric strite, 

 which are aggregated into folds upon the lower and anterior part of the shell. 

 On the cardinal slope these undulations are less prominent. Interior unknown. 



Four specimens have the following dimensions respectively : Length 70, 

 63, 35 and IG mm. ; height 28, 26, 16 and 7 mm. 



This species is comparatively longer than G. Hamiltonensis and G. rugosa, and 

 the concentric striae are finer and strongly fasciculate, while the anterior end 

 is much longer. Compared with G. Chemungensis, the beaks are more distant 

 from the anterior end, the umbonal ridge is slightly curved, while in that 

 species it is very rigid ; the posterior extremity is wider. 



Formation and localities. In the shales of the Hamilton group, associated with 

 Paracyclas lirata, Chonetes scitula, Spirifera mucronata and Hyolithes aclis, at Cop- 

 ley's quarry, Oneonta, and near Mount Upton, N. Y. 



GONIOPHOKA TRIGON.\, n. Sp. 



PLATE XUI, FIG. li ; AND i'LATE XLIV, FIG. 9. 



Ooniophora gUibra, Hall (error for G. OUmcus). Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 



44, fig. 9. 1883. 



Shell large, trapezoidal; body sub-trigonal; length twice the height; basal 

 margin sinuate anterior to the middle, curving gently toward the post-basal 

 extremity and more rapidly to the anterior ; posterior margin obliquely 

 truncate ; cardinal line short, essentially straight ; anterior end large, slop- 

 ing somewhat abruptly from the umbo and narrowly rounded below, limited 

 posteriorly by a broad undefined sirms. Shell convex below, gibbous above ; 

 cardinal slope slightly concave, descending abruptly from the umbonal ridge 

 and gently rising toward the cardinal line. 



Beaks at about the anterior third ; umbo very prominent ; umbonal ridge 



