Maryland Geological Survey 559 



Genus SCHUCHERTELLA Girty 

 SCHUCHERTELLA CHEMUNGENSIS (Conrad) 



Plate XLIX, Figs. 19-22 ; Plate L, Figs. 1-3 



Streptorhynchus cUemungensis Hall, 1867, Paleontology of New York, vol 



iv, p. 67, pis. iv, ix, x. 

 Orthothetes chemungensis' Hall and Clarke, 1892, Ibid., vol. viii, pt. 1, pis. 



X, xi. 

 Schuchertella chemungensis Grabau and Shimer, 1909, N. Amer. Index Fos., 



vol. i, p. 230, fig. 281. 



Description. — This is a shell attaining considerable size, often with the 

 umbonal region more or less distorted from irregular growth, due in 

 part at least to early cementation to foreign objects by the beak of the 

 ventral valve. The shell, however, may be entirely free from evidence of 

 such distortion and in the regularity of its form indicate undisturbed 

 growth. The beak of the ventral valve is generally elevated with a cor- 

 respondingly high cardinal area on which the deltidium is prominent. 

 The ventral valve slopes anteriorly with normally convex but sometimes 

 irregularly concave surface. The dorsal valve is gently convex or flat, 

 also frequently showing irregularities of growth. On the interior of this 

 valve is an erect lamellar cardinal process divided medially, and the four 

 adductor scars are situated about or posterior to the middle of the shell. 

 The exterior of the valves bears more or less regular and coarse subequal 

 plications with occasional concentric interruptions to growth. 



Length 25 mm.; width 35 mm. 



Abundant at certain outcrops of the New York Chemung beds. 



Occurrence. — Jennings Formation, Chemung Member. National 

 Road, 6 miles west of Frostburg; Oakland-Redhouse Eoad; Oakland- 

 Altamont Eoad ; Trout Creek section, near Deer Park Station ; Green 

 Glade Eun; Cherry Creek; Allegany Grove, 1633, 1750, 2000, 2076, 

 2340 ; Ellerslie, Pa., 1310 abundant, 1470 abundant, 1519; National Eoad, 

 on Polish Mountain, 2706 abundant; Town Creek, 3593, 3942, 3982, 4480, 

 4769; 2 miles west of Pawpaw, West Virginia, 3540 common, 4570 ?; 

 Fifteenmile Creek, 1 mile above mouth, 2286. Parkiiead Member. 

 Allegany Grove, 850 ?. 



Collection. — Maryland Geological Survey. 



