408 
PALAEONTOLOGY OF NEW YORK. 
Spathella ventricosa. 
PLATE LXVI, FIGS. 41, 42 
Orthonota ventricosa, White and Whitfield. Proc. Bos. Soc. Nat. Hist., vol. viii, p. 297. 1862. 
Savgu.inolites ventricosus (W. and W.), S. A. Miller. Cat. Am. Pal. Foss., p. 203. 1877. 
In part “ “ “ Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations : PI. 66, 
figs. 36-42. 1S83. 
Shell of medium size, elongate, sub-cylindrical, widest behind ; length more 
than twice the height; basal margin nearly straight, scarcely arcuate in the 
middle, curving into both extremities. Posterior extremity abruptly rounded. 
Cardinal line nearly straight, about half the length of the shell, parallel to 
the basal margin. Anterior end very short, abruptly rounded below. 
Valves very convex, gibbous along the middle and in the umbonal region. 
Beaks anterior, not prominent, small and closely incurved. Post-umbonal 
slope rounded, gibbous. 
Surface marked by fine concentric striae, which are fasciculate, or sub- 
lamellose, upon the umbonal and posterior regions. Interior unknown. 
The two specimens described measure respectively 2(3 and 35 mm. in 
length, and 12 and 16 mm. in height. 
This species resembles the preceding, in many respects, but the anterior end 
is shorter, the valves are more gibbous in the anterior portion, and the lamelli- 
form striae are not so strongly marked. 
Formation and locality. In the Yellow sandstones, at Burlington, Iowa. 
