and slightly incurved, while the visceral region is flattened. The 

 shell is divided into two prominent lobes by a deep., narrow sinus, 

 and the entire surface is covered with fine, often obscure, radiating 

 striae, with small, indistinct concentric wrinkles covering the visceral 

 region and ears; a few spines are scattered over the surface, two of 

 which are generally located near the center of the valve, one on either 

 side of the sinus. 



Dimensions. Length 12.7 mm., length of hinge line 14 mm., 

 greatest width of valve below hinge line 13.5 mm., convexity 9 mm. 



Remarks. Marginifera wabashensis is the common Ohio fossil 

 which has been described and figured in various Ohio reports as Prod- 

 uctus longispinus. 1 It likewise agrees very closely with the geniculate 

 forms from Colorado described and figured by Girty as M. wabashensis 

 var. 2 



Horizon and locality. Lowellville limestone: near Holbein, 

 Muskingum County (Locality 20), r; Lowellville, Mahoning County 

 (Locality 22) c. Boggs limestone: universally distributed, c. Abun- 

 dant and universally distributed in the Lower Mercer and higher 

 Pottsville members. 



Genus Spiriferina D'Orbigny 

 Spiriferina kentuckyensis (Shumard) 



1852 Spirifer octoplicata ? Hall, Stansb. Exped. to Gt. Salt Lake, p. 409, PI. 4, 



Figs. 4a, b. 



Carboniferous: Missouri River, near Weston. 

 1855 Spirifer Kentuckensis. Shumard, Geol. Rep. Mo., p. 203. 



Coal Measures: On the Missouri River near Weston, and Grayson County, 



Kentucky. 



Description. This species is common in the Lower Mercer 

 limestone and also in the higher members of the Pottsville formation 

 but is rare in the lower horizons. It shows considerable variation 

 in size and shape as well as in the length of the hinge line and the 

 number of plications present. A number of small individuals from 

 the Harrison and Sharon ores have been referred rather doubtfully 

 to this species, all of which are in an imperfect state of preservation. 

 The surface is finely punctate and is covered with concentric lamellae, 

 while five plications are present on either side of the fold and sinus. 

 The forms from the marine limestones can easily be recognized by the 

 long, extended hinge line, by the prominent fold and sinus, marked 

 centrally by a small furrow and plication respectively, and by the 

 numerous regular concentric lines covering the surface. Eight to 

 ten plications mark the area on either side of the fold and sinus. 



Dimensions. A specimen of average size from the Harrison ore 

 measures: length 7 mm., width 11 mm., convexity of the ventral valve 



iHerrick, C. L., Bull. Den. Univ., Vol. 2, p. 48, pi. 2, Figs. 25, 27, 28, 1887. 



Mark, C. G., Bull. Den. Univ., Vol. XVI, PI. 8, Fig. 7, 1911. 



Mark, C. G., Geol. Surv. Ohio, Fourth Ser., Bull. 17, p. 302, PL 13, Fig. 8, 1912. 

 2 Girty, H. G., Prof. Paper, U. S. Geol. Surv, No. 16, p. 375, pi. 5, Figs. 8, 8a, 1903. 



55 



