502 PALJEONTOLOGY OF NEW YORK. 



ties. Posterior extremity rounded, nearly vertically sub-truncate above. 

 Cardinal line slightly arcuate. Anterior end short, declining rapidly from 

 the beaks and abruptly rounded below. 



Valves depressed-convex in th,e lower and posterior portions, becoming 

 convex in the umbonal region. 



Beaks at about the anterior fifth, small and closely appressed. Umbonal 

 slope not defined. 



Surface marked by fine striae of growth which are fasciculate on the body 

 of the shell and form undulations at irregular intervals. Interior unknown. 



A specimen has a length of 35 mm. and a height of 17 mm. 



This species somewhat resembles G. depressus, but the beaks are farther from 

 the anterior extremity, the cardinal line is not oblique, and the valves are nar- 

 rower behind. 



Formation and locality. In the Yellow sandstones at Burlington, Iowa. 



ELYMELLA, n. g. 

 Eltmella fabalis, n. sp. 



PLATE XL, FIGS. 5, 9. 



In part ModUnaorphaf hyatea. Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 40, figs. 



5-11. 1883. 

 Not " " " Prelim. Notice Lamellibranchiata, 2, p. 79. 1870. 



Shell small, sub-elliptical, narrower in front ; length more than one-half 

 greater than the height; basal margin regularly convex, curving more 

 gently to the anterior and more abruptly to the posterior. Posterior end 

 symmetrically rounded ; cardinal margin nearly straight, gently sloping 

 posteriorly. Anterior end very short, declining abruptly from the beak and 

 narrowly rounded below. Lunule deeply impressed. 



Valves regularly convex posteriorly, becoming gently gibbous in the 

 middle and umbonal region. 



Hinge-line direct, about half the length of the shell. 



Beaks anterior, rounded and closely appressed. Umbonal ridge not defined. 



