516 PALAEONTOLOGY OP NEW YORK. 



AMNIGENIA, Hall. 1883. 

 Amnigenia Catskillensis. 



PI.ATK XL, FIGS. 1-4; AND PLATE LXXX, KIU. 12. 



Cyprlcarditm CaUkVlensiK Vanixkm. Geol. Surv. N. Y., Rep. Third Dist., p. 186. t. .52, fig. 1. 1S42. 



Modiinnorphn " " S. A. Millkk. Cat. Am. PaL Fobs., p. 196. 1877. 



Amnigenia " " Hali,. Pal. N. Y , voL v, pt. 1. Plates and Explanations : PI. 40, 



figs. 1-4 ; PI. 80, fig. 12. 18S3. 

 Cyjiricarditm augiuifnta, Vanisskm. Geol. Surv. N. Y., Rop. Thii-d Dist., p. 186, t. .52, fig. 2. 1842. 

 ^ofVumutrpha " " S. A. Millkk. Cat. Am. Pal. Foss., p. 196. 1877. 



Modiola angusta (Co.nrad, in eiror), Dana. Manual of (leology, 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 hinge-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 clo.se beneath the upper margin of the shell. The left valve shows 

 a double fold along the cardinal margin Ix'hind tiie 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 Vancxem as Cypricardites angustata, measures 104 mm. in lengtli 



AuoDST, 1885. 



