MEDINAN, NIAGARAN, AND CHESTER FOSSILS 
57 
Straparollus (?) pervetustus (Conrad) 
Plate XIV y fig. 6 
Cyclostoma ? pervetusta Conrad, Ann. Rep. New York State 
Geol. Surv., 1838, p. 113; ibid., 1839, p. 65. 
Pleurotomaria pervetusta Hall, Pal. New York, 2, 1852, p, 12, 
pi. 4 (bis), figs. 3 a-d. 
Euomphalus pervetustus Hall, Geol. New York, 4, 1843, 
p. 48, figs. 1, 2; tab. ill. 2, figs. 1, 2. 
Straparollus pervetustus D’Orbigny, Prod, de Pal., 1, 1849, 
p. 30 (gen‘. ref.). 
Euconia (?) pervetusta Grabau and Shimer, N. A. Index 
Fossils, 1, 1909, p. 642, fig. 874. 
Shell 9 mm. wide and 7.5 mm. in height, with the spire rising 
3 mm. above the last whorl near the aperture. In the specimeu 
figured by Hall the width is 8 mm., the height is 6 mm., and the 
elevation of the spire above the aperture is about 2.5 mm. The 
vertical outline of the spire is rounded, the lowest volution per- 
mitting slightly more than half of the preceding volution to be 
seen, while toward the apical end less and less of the preceding 
volutions remains visible. About five volutions are present. 
Viewed from the exterior of the shell, these volutions appear 
circular in cross-section, but along vertical sections of the shell 
it is seen that later volutions are in contact with earlier volutions 
in such a manner that the inner half of the upper outline of the 
lower volution comes in contact with the outer half of the lower 
outline of the preceding volution along a lunate curve with its 
concave side facing upward and inward. Toward the aperture 
this lunate line of contact may be 2.5 mm. in width. At the 
base of the specimen there is an umbilicus 1 mm. in diameter. 
It is not known to what extent the interior of the umbilicus is 
lined by a callous deposit, if any be present. No trace of sur- 
face markings of any kind have been discovered. 
Locality and formation. — At Medina and Lockport, in the 
Grimsby sandstone member of the Medinan. 
Remarks. — Until traces of a slit-band are discovered in this 
species it seems inadvisable to refer it to Pleurotomaria or to 
