MARYLAND GEOLOGICAL SURVEY 239 



HEBERTELLA VULGARIS Raymond 

 Plate XXXVIII, Figs. 1-5; Plate XLI, Fig. 18 



Hebertella vulgaris Raymond, 1911, Ann. Carnegie Mus., vol. vii, No. 2, 

 p. 242, pi. xxxvi, figs. 2-5, text figs. 15-18, 22. 



Description. " Valves nearly equally convex, outline transversely oval, 

 hinge of variable length, but always less than the greatest width. Sides 

 and front rounded. Some specimens have a broad shallow sinus in the 

 pedicle valve, while others have that valve evenly convex, or merely 

 flattened toward the front. The brachial valve usually shows a narrow 

 but not deep sinus, which extends from the beak nearly or quite to the 

 front. The line in which the two valves meet is usually straight, but in 

 those specimens which have a sinus in the pedicle valve and not in the 

 brachial, the front is sinuate. Mature specimens usually have from 60 to 

 90 fine striae on each valve. The striae increase both by bifurcation and 

 implantation. The cardinal area of the pedicle valve is high and slightly 

 incurved, the delfchyrium apparently open. The teeth are supported by 

 thin lamellae, between which are the scars of the muscles. In the brachial 

 valve there is a low median septum which expands at the posterior end, 

 forming a platform, in the middle of which is the small linear cardinal 

 process. In front of this platform are two pairs of deep adductor scars. 

 The dental sockets are narrow and deep." Eaymond, 1911. 



Occurrence. STONES RIVER LIMESTONE (Middle division). Cham- 

 bersburg, Pennsylvania. 



CHAMBERSBURG LIMESTONE (Caryocystites bed). Fort Loudon and 

 near Blue Spring, Pennsylvania. 



An abundant fossil in the Chazyan rocks of New York, Canada, and 

 Tennessee. 



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



HEBERTELLA BELLARUGOSA (Conrad) 

 Plate XLI, Fig. 6 ; Plate XLV, Figs. 10-12 



Orthis bellarugosa Conrad, 1843, Proc. Acad. Nat. Sci., Phila., vol. i, p. 333. 



Orthis bellarugosa Hall, 1847, Pal., New York, vol. i, p. 118, pi. xxxii, fig. 3. 



Orthis (Hebertella ?) bellarugosa Winchell and Schuchert, 1893, Geol. Min- 

 nesota, vol. ili, p. 434, pi. xxxiii, figs. 1-4. 



Hebertella bellarugosa Raymond, 1911, Ann. Carnegie Mus., vol. vii, No. 2, 

 p. 245, pi. xxxvi, figs. 8, 9, text figs. 19, 20. 



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