328 Report of the State Geologist. 



from other species by the peculiar deflection of the anterior por- 

 tion of the shell considerably below the plane of the lateral 

 margins. 

 Clinton group. Near Hamilton^ Ontario, 



Lingulops Granti. 

 Plate 1, figs. 7, 8. 

 Lingulops Granti, Hall. Palaeontology of N. Y., vol. YIII, pt. 1, p. 173, pi. 

 iv k, figs. 14, 15. 1892. 



Shell small, linguloid in external aspect. Outline elliptical 

 subacuminate at the posterior extremity. External surface 

 marked by faint, elevated, equidistant concentric lines. Margin 

 of contact broad and conspicuous about the entire periphery. 

 On the interior of the pedicle-valve the margin is broadest 

 beneath the beak and slightly grooved on its posterior edge for 

 the passage of the pedicle. The central and lateral muscular scars 

 are elevated on a well-developed platform, the ante-lateral margins 

 of which meet each other at an acute angle. In the brachial 

 valve the posterior margin is also broad and faintly grooved, the 

 platform more conspicuously developed both in length, width and 

 height than in the other valve, while the muscular scars have 

 essentially the same arrangement. In neither valve do the speci- 

 mens at hand afford evidence of the arched parietal impressions 

 seen in the other species of the genus. Length of an average 

 specimen, 6 mm., width, 3 mm. 



This species differs from Z. Whitfieldi and L. Norwoodi^ not 

 only in the absence of the parietal scars, but also in the develop- 

 ment of the muscular area of the pedicle-valve into a distinct 

 platform, and in the absence of the anterior longitudinal septum 

 in the pedicle-valve. 



Niagara group. Hamilton^ Ontario. 



Monomerella Greenii. 



Plate 1, figs. 9-14. 



Monomerella Greenii, Hall. Palaeontology of N. Y., vol. VIII, pt. 1, p. 174, 

 pi. iv d, figs. 5-10. 1892. 



Shell enlongate-subovate. Yalves comparatively shallow; 

 shell substance relatively thin. Surfaces of contact very broad, 

 especially toward the posterior portion of the shell. Pedicle- 

 valve with an erect but not high cardinal area, which is continu- 



