DESCRIPTION OF SPECIES 209 



anterior extremity, which in the latter species is blunt and somewhat 

 truncated. It is very similar to A. kessleriana (Mather), but may be 

 distinguished by its less centrally located beaks and its more produced 

 anterior end (the long pointed one), which give to the shell a decidedly 

 more transversely-elongate form. 



Horizon and locality. Sharon* ore: Lick Run, Scioto County, 

 Locality 2, r. The specific name is given in honor of Dr. J. A. Bow- 

 nocker, State Geologist of Ohio. 



Genus Parallelodon Meek 



Four species of Parallelodon are among the collections of Pottsville 

 fossils studied, P. carbonarius, P. obsoletus, P. sangamonensis, and 

 P. tenuistriatus, all of which are of common occurrence except P. san- 

 gamonensis. The genus extends from the Harrison ore at the base 

 throughout the entire formation, but occurs most abundantly in the 

 Lower Mercer and McArthur members. 



Parallelodon carbonarius (Cox) 



1857 Area carbonaria. Cox, Geol. Surv. Ky., Vol. 3, p. 567, PI 8, Fig. 5. 



Coal Measures: Kentucky. 

 1887 Macrodon caibonaria. Herrick, Bull. Den. Univ., Vol. 2, p. 32, PL 4, Figs. 14. 21. 



Coal Measures: Flint Ridge, Ohio. 



Description. Parallelodon carbonarius is particularly common in 

 the Lower Mercer limestone although it occurs as low as the Boggs; it 

 is also present in the higher members. It is characterized by surface 

 sculpture of prominent, regular, radiating plications which become con- 

 siderably larger and stronger on the flattened posterior portion below 

 the hinge line. 



Dimensions. The dimensions of a specimen of average size from 

 the Boggs member are: length 20 mm., height from beak to opposite 

 margin 9 mm. 



Horizon and locality. Boggs member: Muskingum County, Lo- 

 cality 26, c. Widely distributed in the Lower Mercer limestone, c. 

 Upper Mercer member: Muskingum County, Locality 68, r. Widely 

 distributed in the McArthur member, c. 



Parallelodon obsoletus (Meek) 

 PL XI, figs. 1, 2 



1871 Macrodon obsoletus. Meek, Rep. Regents Univ., W. Va. 



Lower Coal Measures: Monongahela County, West Virginia. 

 1875 Macrodon obsoletus. Meek, Pal. Ohio, Vol. II, p. 334, PL 19, Fig. 9. 



Coal Measures: Newark, Ohio. 



