1897.] NEW YORK ACADEMY OF SCIENCES. 259 



1891. Athyris subquadrata, Whitfield, Ann. N. Y. Acad. Sci., 



Yoi. 5, p. 585, PL 14. figs. 1-3. 

 1895. Athyris subquadrata, Whitfield, Geol. Surv. Ohio, YoI. 

 7, p. 472, PL, 10, figs. 1-3. 



Shell of medium size or less, subquadrate in outline and 

 strongl}' trilobate, proportional length and breadth varjnng from 

 longer than wide to ■wider than long. 



Pedicle valve most ventricose, beak prolonged and incurved, 

 extremity truncated and perforated by a circular foramen of con- 

 siderable size. Mesial sinus subangular, deepl}' impressed to- 

 ward the front, where the shell is bent dorsall}^ in a lingual ex- 

 tension, bounded laterally b}^ rounded ridges and extending to 

 the beak, though faintl}' marked in the posterior portion of its 

 length. 



Brachial valve most rotund on the umbo, beak obscure, in- 

 curved. The middle of the valve strongly elevated in ftont, form- 

 ing an abrupt rounded mesial fold, which is scarcely defined pos- 

 terior to the middle point of the length of the valve. Sides of 

 the shell impressed on each side of the fold, forming a well- 

 marked sinus on each side and giving the valve a strongl}- tri- 

 lobed appearance. 



Surface marked by concentric lines of growth which are con- 

 fined to the anterior portion and are often crowded toward the 

 margin. 



As this species occurs in the Batesville beds it is in the form 

 of internal casts in which the dental lamellae are represented by 

 a pair of curved slits, which converge both posteriorly and an- 

 teriorly. The specimen figured is from the U. S. Geological 

 Survey collection and has been loaned for illustration by Pro- 

 fessor H. S. Williams. 



EUMETRIA VERNEUILANA Hall. 



1856. Retzia verneuilayxa, Hall, Trans. Albany Inst., YoL 4, p. 9. 

 1858. Retzia verneuilana, Hall, GeoL Iowa, YoL 1, pt. 2, p. 657, 

 PI. 23, figs. la-d. 



1882. Eumetria verneuilana^ Whitfield, BulL Am. Mus. Nat. 

 Hist., YoL 1, p. 50, PL 6, figs. 28-30. 



1883. Eumetria verneuilana, Hall, 12th Rep. GeoL Surv. Ind., 



p. 335, PL 29, figs. 28-30. 

 1895. Eumetria verneuilana, Hall and Clarke, Pal. N. Y., YoL 8, 

 pt. 2, PL 51, figs. 13-26, 34-35, PL 83, figs. 26-27. 

 Shell longitudinally' ovate, valves almost equall}' convex, 

 hinge-line v^xy short. 



Pedicle valve most convex towards the beak, which is elevated 



