380 
PALAEONTOLOGY OF NEW-YORK. 
Genus Gypidula (n.g.). 
[ Gr. yvip, vultur ; in allusion to the strongly incurved beak.] 
Generic characters as given on page 373 of this volume. 
Type G. occidentalis. 
Gypidula occidentalis. 
PLATE LVIII. 
Pentamerus occidentalis : Hall, Geology of Iowa, Vol. i, part ii, pa. 514, pi. vi, f. 2. 1858. 
Not “ “ Idem, Pal. New-York, Vol. ii, p. 341. 1852. 
Shell subovoid, gibbous, very inequivalve; hinge-line equalling three- 
fourths the entire width of the shell. 
Ventral valve arcuate, gibbous or ventricose in the upper part; beak 
extended, strongly incurved, obtuse ; fissure large and bordered by a 
distinct area which is vertically striated. The spoon-shaped pit is 
deep, extremely extended ‘and incurved. The middle of the valve, 
below the first third, elevated into a more or less distinot mesial fold 
which is marked by two or three plications. 
Dorsal valve gibbous above, becoming flattened below the middle, some¬ 
times concave at the sides, and the front depressed into a deep and 
more or less distinctly defined sinus. A narrow area extends for about 
two-thirds the length of the hinge-line. 
Surface plicated below by a few rounded or subangular plications which 
become obsolete above; the upper part of the valve marked only by 
concentric striae. 
Geological formation and locality. In strata of the age of the Hamilton group, 
at Independence, Iowa. 
