504 PALAEONTOLOGY OF NEW YORK. 



Compared with E. fabulis, this species has a stronger test, with a greater 

 proportional height and much stronger surface characters. It is similar in 

 many respects to E. patula, but is less oblique, umbonal region more prominent, 

 and the anterior end shorter. 



Formation and localities. In the Hamilton shales ; at Hamburgh-on-the-Lake, 

 Erie county ; Ludlowville, Tompkins county, and Cooperstown, Otsego county, 

 N. Y. 



Elymella levata, n. sp. 



Shell of medium size, sub-elliptical, wider behind ; length about twice the great- 

 est height ; basal margin nearly straight, scarcely sinuate anterior to the mid- 

 dle, curving regularly to the anterior and posterior ends. Posterior extrem- 

 ity symmetrically rounded, the greatest extension being below the middle of 

 the height. Cardinal line straight for less than half the length of the shell, 

 and curving posteriorly. Anterior end very short, declining abruptly from 

 the beak and rounded below. Lunule well-defined. 



Valves regularly convex on the posterior half, becoming gibbous in the 

 middle and umbonal region. 



Beaks sub-anterior, small, appressed. Umbonal slope prominent, not 

 strongly defined, becoming merged in the general convexity posterior to the 

 middle of the shell. The valves are flattened just below the beaks, and a 

 slight depression continues to the base, producing a gentle sinuosity in the 

 margin. Post-cardinal slope wide. 



Surface marked by fine striae of growth which are more or less fasciculate. 

 The striae curve over the posterior slope and extend forward along the car- 

 dinal line nearly parallel with it. The substance of the shell is marked by 

 distinct radii, which are sometimes obscurely defined upon the surface. 



The specimen described has a length of 27 mm. and a height at the pos- 

 terior extremity of 14 mm., and at the beaks of 10.5 mm. 



This species is proportionally more elongate than any other in the genus, 

 and is also distinguished by the flattening which extends from the beaks to 

 the base, producing a slight sinuosity in the margin. 



