608 Systematic Paleoxtology — Upper Devoxiak 



rior to tlie iniddlc of the lengtli, abrupth' reeurviug at the postbasal 

 extremity and obliquely trinicate above. Cardinal line nearly straight, 

 scarcely declining posteriorly. Anterior end short, obliquely truncate 

 above at the lunule, and abruptly rounded below, having an angle at the 

 Junction of the two lines. Valves regularly convex in the lower and 

 posterior portions, becoming gibbous above and especially on the post- 

 umbonal slope. Beaks subanterior, prominent, large, strongly incurved. 

 ITmbonal slope obtusely sub-angular, and extending to the posterior ex- 

 tremity, with a faint indication of a plication on the postcardinal slope. 

 Valves marked by a distinct cincture extending from the beak, more or 

 less obliquely, to the basal margin anterior to the middle of its length. 

 Surface marked by fine concentric strige, which are obscurely visible in 

 the cast; and by strong concentric undulations which mark the anterior 

 and central portion of the valves, becoming obsolete on the umbonal 

 ridge. Interior unknown." Hall, 1885. 



Length 29-44 mm. ; lieight 10-15 mm. 



The individuals observed in Maryland differ slightly from those 

 figi;red by Hall from New York though they approach them closely. 



Occurrence. — Jennings Formation, Woodmont Member, Ithaca 

 Fauna. Yellow Springs, West Virginia, 665. 



Collection. — Maryland Geological Survey. 



Grammysia undata Hall 



Edmondia undata Hall, 1S83, Pal. of N. Y., vol. v, pt. ii, Plates and Ex- 

 planations, pi. Ixiv, fig. 30. 



Grammysia undata Hall, 1885, Pal. of N. Y., vol. v, pt. i, ii, p. 379, pi. Ixi, 

 Fig. 23, pi. Ixiv, fig. 30; pi. xciii, fig. 21. 



Grammysia undata Grabau and Shimer, 1909, N. Amer. Index Foss., vol. i, 

 p. 383, fig. 28. 



Description. — " Shell below tlie medium size ; ovate subelliptical ; 

 length about one-third greater than the height; basal margin gently 

 curving, nearly straight, and slightly constricted anterior to the middle 

 of its length. Posterior margin curving upward to about the middle of 

 its height, above which it is obliquely subtruncate. Cardinal line straight, 

 more than two-thirds the length of the shell, slightly declining posteriorly. 



