322 
PALAEONTOLOGY OF NEW YORK. 
The specimen has a length of 21 mm., height 18 mm. and a depth to both 
valves of 14 mm. 
This species is distinguished by its broadly ovate form, very prominent 
umbones and short anterior end. 
Formation and locality. In the Chemung group, at Mansfield, Pa. 
Nucula diffidens, n. sp. 
PLATE XLV, FIGS. 12, 14. 
In part Nucula Ranclalli, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 45, fig-s. 5-16. 
1883. 
Shell of about medium size; narrowly ovate; length less than twice the 
height; basal margin less curved toward the anterior and more curved 
toward the posterior. Posterior extremity narrowly rounded. Cardinal line 
declining posteriorly. Anterior end short, and abruptly rounded below. 
Valves gibbous in the middle and above. 
Beaks at the anterior third, prominent. Umbonal slope obtusely sub- 
angular, merging into the general convexity of the valve before reaching 
the posterior margin. 
Surface marked by fine concentric striae, which are often irregularly 
fasciculate, especially toward the margin. Muscular impressions strongly 
marked. Teeth well developed. 
Three specimens measure respectively 19, 17 and 16 mm. in length, and 
11, 10 and 9 mm. in height. 
This species resembles some of the smaller forms of N. Randalli, but the 
posterior end is wider, beaks less elevated and the umbonal slope is not so 
strongly defined. 
Formation and localities. In the shales of the lower Chemung group at Ithaca, 
and in Chemung county, N. Y. 
Nucula globularis, n. sp. 
PLATE XCIII, FIG. 6. 
Shell robust, of medium size ; sub-globose ; length somewhat greater than the 
height; basal margin regularly rounded, abruptly curving at both extrem- 
