DESCRIPTION OF SPECIES 223 



Description. An excellent cast of the left valve of Schizodus amplus 

 is among the collections of Boggs fossils at hand. The species is char- 

 acterized by its large size, quadrangular form, anteriorly placed beak, 

 and long, straight cardinal margin posterior to the beak. In the speci- 

 men studied the pallial line, the large oval adductor scar, and the anter- 

 ior pedal muscular impression are distinctly marked. 



Dimensions. The figured specimen from the Boggs limestone 

 measures: length about 70+ mm., height 56.5 mm., thickness of left 

 valve 14 mm. (somewhat crushed). 



Horizon and locality. Boggs limestone: Muskingum County, near 

 Hopewell P. O., Locality 26, r. 



Schizodus affinis Herrick 

 PL XII, fig. 17 



1887 Schizodus affinis. Herrick, Bull. Den. Univ., Vol. 2, p. 41, PL 4, Figs. 22, 22a. 

 Coal Measures: Flint Ridge, Ohio. 



Remarks. Schizodus affinis is a common fossil of wide strati- 

 graphic range in the Potts ville rocks of this State; it is found from the 

 Harrison ore at the base to the McArthur member near the top. The 

 species exhibits considerable variation in size; an individual of average 

 size from the Harrison ore measures: length 17.5 mm., height 14.2 mm., 

 thickness of left valve 4.8 mm. 



Horizon and locality .~ Harrison ore: Jackson County, Locality 1, 

 r. Boggs member: Muskingum County, Localities 26, 28, c. Lower 

 Mercer member: Muskingum County, Localities 43, 45, r; Licking 

 County, Localities 46, 47, r. McArthur member: Jackson County, 

 Locality 80, c; Vinton County, Localities 84, 85, c. 



Schizodus cuneatus Meek 

 PL XIII, figs. 1, 2 



1875 Schizodus cuneatus. Meek, Pal. Ohio, Vol. II, p. 336, PL 20, Fig. 7. 

 Lower Coal Measures: Putnam Hill and Flint Ridge, Ohio. 



Description. Although this large species of Schizodus has been 

 found only in the Lower Mercer member where it is of rather rare 

 occurrence, nevertheless some excellently preserved specimens have 

 been obtained. It is easily distinguished by its large size, its high 

 pointed beaks, its short anterior end, and its extremely produced post- 

 erior-inferior angle. 



Dimensions. The largest specimen found measures: length 50 mm., 

 height at beaks 41 mm., convexity of right valve 14 mm. 



