Maryland Geological Survey 549 



Order NEOTREMATA 



Superfamily DISCINACEA 



Family DISCINIDAE 



Genus ORBICULOIDEA d'Orbigny 



OrBICULOIDEA cf. MEDIA (Hall) 



Plate XLVTI, Figs. 9, 10 



Discina media Hall, 1863, 16th Rept. N. Y. State Cab. Nat. Hist., p. 27. 

 Discina media Hall, 1867, Pal. of N. Y., vol. iv, p. 20, pi. li, figs. 25-29. ' 

 OrMculoidea media Hall and Clarke, 1892, Pal. of N. Y., vol. viii, pt. i, pi. 

 iv, figs. 15-17. 



Description. — Shell snbelliptical to subeirciilar. Small. Dorsal valve 

 low conical, umbo excentric, small, acute. Surface with concentric 

 striae. Interior of dorsal valve and ventral valve not observed. The 

 shell figured is somewhat crushed, causing the umbo to appear more 

 nearly central than it is, and the outline more elliptical than it should be. 



This species of wliich but two individuals have been observed, suggests 

 0. media which occurs both in the Hamilton and Upper Chemung faunas 

 of New York. More material is needed to permit confident identification. 



Length 7 mm.; width 8 mm. 



Occurrence. — Jennings Formation, Parkhead Member. Williams 

 Koad, east of Cumberland, 1393; National Eoad on Polish Mountain in 

 soft olive shale with Chonetes lepidiformis. Woodmont Member, Ith- 

 aca Fauna. Fifteenmile Creek, 1 mile above mouth, 1446. 



Collection. — Maryland Geological Survey. 



Superfamily CRANIACEA 

 Family CRANIIDAE 



Genus CRANIELLA CEhlert 

 Craniella hamiltoni,u Hall ' 



Plate XLVII, Figs. 11-13 



Description. — Shell transverse conical. Umbo subcentral. Dorsal 

 valve quite convex. Adductor muscular scars pronounced, close together 



' For synonymy see page 131. 



