512 PALEONTOLOGY OF NEW YORK. 



but the chanicters of the hinge are very distinctive, and there is no defined 

 unibonal ridge extending to the post-inferior extremity. 



Formation and locality. In the shales of the Hamilton group, in Hardy 

 county, Va. 



CLINOPISTHA, Mkek and Worthen. 1870. 



Clinopistha subnasuta. 



PLATE LI, FIGS. 32,83; AMD PLATE XCV, FIG. 81. 



Tdlinomya [Dystactella] svbtuisiita. Halt, and Whitkibld. Twenty-fourth Ann. Rep. N. Y. State Mus. 



Nat. Hist., .p. 191. 1872. 

 Dyxtactella siibnaimta (Hall and Whitkield), S. A. Millbh. Cat. Am. Pal. Foss., p. 190. 1877. 



" " " " Hall. Pal. N. Y., vol. v, pt. 1. Plates and ExplanationB : 



PI. 51, figs. 32, 33. 1883. 



Shell small, narrowly sub-elliptical, nearly straight on the basal side ; length 

 about twice the height. Basal margin nearly straight, curving abruptly to 

 the anterior and more gently to the posterior end. Posterior extremity 

 rounded. Cardinal line gently arcuate. Anterior end short, sub-nasute, 

 declining from the beaks and narrowly rounded below. The place of the 

 lunule is occupied by a fold or callosity which is distinctly limited by the 

 margins of the valve. 



Valves moderately convex below and posteriorly, gibbous in the umbonal 

 region. 



Beaks at about the anterior third, small, closely appressed. Umbonla 

 slope convex, not defined. 



Test thin. Surface marked by somewhat regular, fine, thread-like strige 

 of growth, which in the perfect condition of the shell may have been lamel- 

 lose, and are fasciculate on some individuals. 



The hinge shows some appearance of having been crenulated, but the con- 

 dition of the specimens is such as not to admit of positive determination. 

 Muscular impressions distinct. Pallial line entire, marked in the cast by a 

 series of radiating pustules. 



Three specimens measure respectively 21, 26 and 27 mm. in length, and 

 12, 13 and 13 mm. in height. 



