002 Systematic Paleoxtology— Upper Devoniax 



1708 abundant, 1725, 3009; National Eoad, on Polish Mountain, 2016, 

 2159, 2706 common, 2929 abundant, 2949; Town Creek, 338-t, 3404, 

 3453, 3584, 2 miles west of Pawpaw, West Virginia, 2190; National 

 Road, on Green Ridge, 3400; Millstone, 2253 ?, 2322. Paekiiead 

 Member. Rocky Run ; Turners Road, 7 miles southeast of Cumber- 

 land; Williams Road, east of Cumberland, 1393?; Williams Road, 

 on Polish Mountain, 1289, 1524, 1632, 1660 common; National Road, 

 on Polish Mountain, 1196, 1625; 2 miles north of mouth of Town 

 Creek, 1723 common, 1917 common, 1949; Town Creek, 1729, 1863 

 abundant; 3 miles west of Pawpaw, West Virginia, 1612, 1794 com- 

 mon; east of Little Orleans; Fiftecnmile Creek, 1 mile north of 

 Little Orleans, 1713, 1746, 1766 common, 1774; Sideling Hill Creek 

 2y2 miles above mouth, abimdant; National Road west of Tonoloway 

 Ridge; Hancock, 1600; Millstone, 1600; Berkeley Springs, West Vir- 

 ginia, 1769; Yellow Springs, West Virginia, 1600. 

 Collection. — Maryland Geological Survey. 



Genus AMBOCOELIA Hall 



Amboccelia umbonata (Conrad) 



Plate LIX, Figs. 3-7 



Orthis umbonata Conrad, 1842, Jour. Acad. Nat. Scl., Phila., vol. viii, p. 264, 



pi. xiv, fig. 21. 

 Ambocwlia umbonata Hall, 1867, Pal. of N. Y., vol. iv, p. 259, pi. xliv, figs. 



7-18. 

 Ambocwlia umbonata Hall and Clarke, 1894, Pal. of N. Y., vol. viii, pt. ii, 



pi. xxix, fig. 17; pi. xxxix, figs. 4-9. 

 Ambocwlia umbonata Grabau and Shimer, 1909, N. Amer. Index Foss., vol. i, 



p. 343, fig. 438. 



Description. — Shell small, convexo-plane, suborbicular in outline. Ven- 

 tral valve gibbous with umbo elevated and incurved. Median sinus 

 distinct. Cardinal area arched. Dorsal valve depressed convex or flat. 

 Surface of both valves smooth or marked only with fine concentric striae. 

 On the interior, the ventral valve has strong teeth, the dorsal valve has 

 strong crural plates and a quadripartite muscular scar situated in front 

 of the middle. 



Length 6 mm. ; width 6 mm. 



