Horizon and locality. Lowellville limestone: generally distributed 

 throughout the member, a. Present in the Lower Mercer and higher 

 Pottsville members. 



Genus Ambocoelia Hall 

 Ambocoelia planoconvexa (Shumard) var. 



1855 Spirifer planoconvexa. Shumard, Geol. Rep. Mo., p. 202. 



Upper Coal Measures: On Missouri River, near mouth of Platte River. 



Description. A small brachiopod belonging to the genus Ambo- 

 coelia is common in the black shales on the Lowellville horizon along 

 Poverty Run, Muskingum County. The form suggests identification 

 with A. planoconvexa (Shumard), but fairly constant differences 

 render such identification doubtful. The Lowellville form is small, 

 about one-half the size of A. planoconvexa, narrower, with a shorter 

 hinge line which equals only about one-half the greatest width of the 

 shell. The beak of the ventral valve is somewhat broader and less 

 elevated; it is marked by a faint, narrow sinus which becomes evident 

 near the beak. However, occasionally specimens of A. planoconvexa 

 are found on which the differences mentioned above are not very 

 evident, so that a new species or even a new variety name for the 

 Lowellville form may not be justifiable, especially as the material 

 at hand is not in first-class condition. 



Dimensions. A large ventral valve measures: length 4.5 mm., 

 width 5.5 mm.., convexity 2.2 mm. A dorsal valve of average size 

 measures: length 2.2 mm., width 2.7 mm. 



Horizon and locality. Lowellville member: Poverty Run, Mus- 

 kingum County (Locality 19), c. 



Genus Squamularia Gemmellaro 

 Squamularia perplexa (McChesney) 



1856 Spirifer lineatus. Hall, Pac. R. R. Rep., Vol. 3, p. 101, PI. 2, Figs. 6-8 (Not 



S.lineatus Martin, 1809.) 



Carboniferous: Pecos Village, New Mexico. 

 1860 Spirifer perplexa. McChesney, Desc. New Pal. Foss., p. 43. 



Upper Coal Measures: Almost every part of the country where rocks 



of that age occur. 

 1899 Reticularia perplexa. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., Pt. 3, 



p. 577, PI. 72, Fig. la. 



Upper Coal Measures: McAlester quadrangle, Indian Territory. 

 1903 Squamularia perplexa. Girty, Prof. Paper, U. S. Geol. Surv.. No. 16, p. 392, 



PL 6, Figs. 8-1 Ic. 



Description. This is an abundant and widely distributed mem- 

 ber of the marine limestones of the Pottsville formation above the 

 Boggs member, although it is rare in the latter horizon. It occurs 

 as a rule as internal casts on which fine concentric bands of spines 

 or traces of them are usually visible. The Ohio specimens are some- 

 what larger than those described by McChesney which seldom obtain 

 a width of more than five-eighths of an inch. A specimen of average 



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