516 
PALAEONTOLOGY OF NEW YORK. 
AMNIGENIA, Hall. 1883. 
Amnigenia Catskillensis. 
PLATE XL, FIGS. 1-4 ; AND PLATE LXXX, FIG. 12. 
Cypricardites Catskillensis, Vanuxem. Geol. Surv. N. Y., Rep. Third Dist., p. 186. t. 52, fig - . 1. 1S42. 
Modiomorpha “ “ S. A. Miller. Cat. Am. Pal. Foss., p. 196. 1S77. 
Amnigenia “ “ Hall. Pal. N. Y , vol. v, pt. 1. Plates and Explanations: PL 40, 
fig-s. 1-4 ; PI. 80, fig. 12. 1883. 
Cypricardites a.vgustata, Vanuxem. Geol. Surv. N. Y., Rep. Third Dist., p. 186, t. 52, fig - . 2. 1842. 
Modiomorpha “ “ S. A. Miller. Cat. Am. Pal. Foss., p. 196. 1877. 
Modiola angusta (Conrad, in error), Dana. Manual of Geology, p. 292, fig. 508. 1863. 
Shell large, elongate-sub-elliptical or narrowly obovate, somewhat arcuate; 
length more than twice the height; basal margin often nearly straight, usu¬ 
ally gently sinuate at about the anterior third and convex on the posterior 
half, sometimes gently convex for the entire length. Posterior extremity 
rounded, obliquely sub-truncate above from the extremity of the cardinal 
line. Cardinal line gently arcuate, rising from the beaks to beyond the mid¬ 
dle of the shell, with a slight alation. Anterior end short, rounded. 
Valves depressed-convex posteriorly, becoming convex in the middle and 
in the umbonal region. 
Beaks sub-anterior, low, appressed, rising but little above the liinge-line. 
Umbonal slope convex, undefined, extending to the middle of the posterior 
extremity. Post-cardinal slope wide, not defined. 
Surface marked by fine concentric striae, which are often strongly fascicu¬ 
late on the posterior, basal and anterior portions. 
Anterior muscular impression large, strong, situated just anterior to the 
beaks and close beneath the upper margin of the shell. The left valve shows 
a double fold along the cardinal margin behind the beaks. 
Three specimens measure respectively 105, 109 and 112 mm. in length, 
40, 39 and 43 mm. in height at the beaks, and 47, 47 and 50 mm. in height 
at the posterior third. A large specimen has a length of 155 mm. and a 
height of 67 mm. A compressed specimen of the form described and 
figured by Vanuxem as Cypricardites angustata, measures 104 mm. in lengthy 
August, 1885. 
