224 POTTSVILLE FAUNA OF OHIO 



Horizon and locality. Lower Mercer limestone: Licking County, 

 Bald Knob, Locality 46, r; Flint Ridge, Locality 47, r. 



Schizodus curtus Meek and Worthen 



1866 Schizodus curtus. Meek and Worthen, Proc. Chicago Acad. Sci., Vol. 1, p. 18. 

 1887 Schizodus curtus. Herrick, Bull. Den. Univ., Vol. 2, pp. 42, 145, PI. 14, Fig. 20. 

 Coal Measures: Flint Ridge, Ohio. 



Remarks. Schizodus curtus appears in the Boggs member, and 

 although relatively rare, it continues throughout the middle and upper 

 Potts ville formation. It is most common in the Lower Mercer and 

 McArthur limestones, but even in the latter members the number of 

 individuals found at any one locality is small. 



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

 calities 26, 27, r. Lower Mercer member: Muskingum County, Locali- 

 ties 39, 43, r; Licking County, Flint Ridge, Localities 47, 48, 49, r. 

 McArthur member: Jackson County, Locality 80, r; Vinton County, 

 Localities 82, 84, r. 



Schizodus mooresi Miller ? 



1889 Schizodus mooresi. Miller, N. Am. Geol. and Pal., p. 511, Figs. 918, 919. 

 Coal Measures: Carbon Hill, Hocking County, Ohio. 



Description. Specimens o'f a very large, thick shelled Schizodus 

 were obtained from the Lower Mercer and McArthur limestones, well 

 preserved except in the posterior portions, which \ are in every case 

 wanting or so badly crushed that no clue to the outline and to the 

 degree of extension in that portion of the valve can be obtained. As 

 these characters are of primary, importance in separating the different 

 species of Schizodus, any identification of these forms with described 

 species must necessarily be extremely uncertain. They can, however, 

 be best compared with S. spellmani Herrick and with S. mooresi Miller, 

 the species in the latter case having been Jmsed upon imperfect specimens 

 in which the posterior end is unknown; the McArthur forms may be 

 referred equally as well to one species as to the other. The first men- 

 tioned form was described from the Lower Mercer horizon at Flint 

 Ridge, while Miller's species came from a horizon a little above or 

 possibly the same as the McArthur and from a relatively near-by lo- 

 cality. Comparisons with specimens from Carbon Hill, which are 

 probably identical with Miller's S. mooresi, have been made, and very 

 little difference could be noted. $. mooresi seems the closer specific 

 reference for the Lower Mercer individuals also, although identifi- 

 cation with this species is necessarily doubtful as the character of the 

 posterior end is unknown. 



