Maryland Geological Survey 389 



Eenssel^eria (Beachia) ovalis (Hall) 

 Plate LXVII, Fig?. 17-19 

 Meganteris ovalis Hall, 1857, Tenth Ann. Rept. N. Y. Cab. Nat. Hist., p. 101. 

 Rensselwria ovalis Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 458, pi. cvi, 



figs. 2a-2l, 18G1. 

 Megalanteris ovalis Hall and Clarke, 1893, iMdcm, vol. viii, pt. ii, p. 280, pi. 



Ixx, figs. 12-22. 

 Megalanteris ovalis Clarke, 1900, Mem. N. Y. State Mus., vol. iii, No. 3, p. 40, 

 pi. V, figs. 13-16. 



Description. — " Shell longitudiually oval, compressed, lateral margins 

 subtruncate and abruptly inflected ; front rather narrowly rounded : 

 ventral valve slightly the more elevated, most prominent along the middle, 

 sloping gradually towards the sides ; beak pointed, arched so as to bring 

 the apex above the hinge-line, but not touching the opposite valve, angular 

 along the lateral slopes: dorsal valve regularly depressed convex; beak 

 incurved. Surface marked by very faint simple radiating stria?, which 

 become obsolete on the upper part." Hall, 1857. 



This is a very rare shell in Maryland and is closely related to R. suessana 

 from which it differs, not only in being larger, but also flatter or thinner, 

 better developed ventral false area, and the absence of striaj. Hall de- 

 scribes the shell with " very faint " strias, but none have been seen in the 

 southern specimens, nor does Clarke show any in the work above cited. 



Length 3.6 cm.; width 3.2 cm. 



This shell is here referred to the subgenus Beachia because it greatly 

 resembles R. suessana and, further, the brachidium in the type of 

 Meganteris is not yet certainly worked out, nor is it known in R. ovalis. 



Occurrence. — Oriskany Formation, Kidgely Member. Cumberland, 

 Knobly Mountain, Maryland ; near AVarren Point, Pennsylvania. 



Collections. — Maryland Geological Survey, U. S. National Museum. 



Genus ORISKANIA Hall and Clarke' 



The brachidium in this genus is unknown, but it is probably very 

 similar to that in the subgeinis Beacliia. Oriskania is readily dis- 

 tinguished from Eensselseria by the hinge-plate which has a median 

 vertical high ridge. Otherwise the general aspect of these shells is more 

 that of Beachia than Eensselseria. Three species are now known of this 



*Hall and Clarke, 1893, Nat. Hist. N. Y., Pal., vol. viii, pt. ii, p. 2G9. 



