MEDINAN, NIAGARAN, AND CHESTER FOSSILS 
75 
latter appear to belong to a distinctly lower horizon, possibly 
corresponding to the Edgewood of western Illinois and eastern 
Missouri. 
Schuchertella subplana brevior Var. nov. 
Plate XIV, fig. 13 
Width of shell at hinge-line 29 mm.; length 18 mm. Pedicel 
valve with a maximum convexity of 1.5 mm. at a distance of 3 
mm. from the hinge-line, flattening out toward both the lateral 
and anterior margins. Radiating striae alternating in size; 
about 8 of the more prominent striae occupy a width of 5 mm. 
along the anterior margin of shell. Brachial valve more evenly 
convex, with the maximum convexity at about two-fifths of 
the length of the shell from the hinge-line. 
Locality and formation.^ — Quarry | mile northeast of Center- 
ville, Ohio; in the argillaceous strata immediately beneath the 
Brassfield limestone. 
Remarks. — In typical Schuchertella subplana (Conrad) the 
ratio of the length to the breadth usually varies from 75 to 90 
per cent, while the form here described has a ratio of only 62 per 
cent.i^ 
The Waldron form, also known under the name Schuchertella 
subplana, is as short as the Centerville form, but the radiating 
striae are coarser. It may be known as Schuchertella subplana 
waldronensis Var. nov. 
Brachyprion sp. 
Plate XIV, fig. 12 
Shell 25 mm. in width, enlarging to 30 mm. along the hinge- 
line, owing to the acute extension of the postero-lateral angles. 
Length 21.5 mm. Only the interior of a valve is at hand 
and this is assumed to be the pedicel valve. The hinge- 
area is 1 mm. in height at the beak. On the inner surface of 
this valve a strong median striation extends from a short dis- 
tance anterior to the beak forward to a point about half-way 
Hall, James, Paleontology of New York: vol. 2, 1852, pi. 53. 
