208 NEW YORK STATE MUSEUM 



Genus liopteria Hall 



[Ety. : /sFo9, smooth; 7crep6v, wing"] 



(1883. Pal. N. Y. v. 5, pt 1, p. 4) 



Shell aviculoid, oblique, subrhomboidal ; anterior end not auricu- 

 late; wing large, extremity produced. Hinge narrow, furnished 



with a slender lateral tooth just pos- 

 terior to the beak and nearly parallel 

 ' I 'i I to the hinge line. Ligament external; 



■'i'f ligamental area narrow, extending 



the entire length of the hinge, marked 

 by fine, sharp, longitudinal striae. Test 

 with concentric striae but without rays. 



Liopteria ( ?) subplana (Hall) (Fig. 

 136). Avicula subplana Hall 

 (1852. Pal.N. 7.2:283, pi. 59) 



, ;""-.. Distinguishing characters. Depressed 



convex surface; similarity of right and 

 X V V left valves; ill defined wing and ear; 



concentric striae; absence of radii. 



Fig. 136 Liopteria (?) subplana 



Found in the Rochester shale at 

 Lockport associated with Pterinea emacerata, etc. (Hall). 

 Probably also at Niagara. The generic reference is provisional. 



Genus lyriopecten Hall 



[Ety.: Xupiov, small lyre; pccten, comb, i. e. the genus Pec- 

 ten] 



(1884. Pal. N. Y. v. 5, pt 1, p. 12) 



Shell inequivalve, with a short hinge line and very small anterior 

 ear. Cartilage in shallow furrows, parallel to the hinge margin. 

 Surface ornamented with rays. 



Lyriopecten orbiculoides (nora. nov.) cf. Avicula (?) or- 

 b i c u 1 a t a Hall (1852. Pal. N. Y. 2 :284, pi. 59) 



Distinguishing characters. Right (?) valve convex; left (?) valve 

 flat; form suborbicular, hinge line short, straight; strong radiating 

 striae cancelated by equally strong concentric striae, forming sur- 

 face similar to Pterinea emacerata. 



