MEDINAN, NIAGARAN, AND CHESTER FOSSILS 
101 
should be dropped, or that Ulrich should be followed in his 
definite choice of a type or of a series of types from a definitely 
known horizon. Ulrich’s three specimens of Cyclonema hilix^^ 
figured first under that name in the Paleontology of Minnesota, 
from Versailles, Indiana, and Waynesville and Clarksville, Ohio, 
are definitely of Richmond age, and their horizon probably was 
that of its Waynesville member. 
Cyclonema gyronemoides Sp. nov. 
Cyclonema bilix varicosum -Foerste, Geol. Surv. Ohio, Pal., 
7, 1893, p. 552, pi. 37A, fig. 9. 
Shell with 3 or 4 volutions, rapidly enlarging, the last volution 
forming by far the greater part of the shell. In most of the 
specimens at hand the spire appears somewhat depressed, simi- 
lar to the spire of Cyclonema daytonensis as figured in 1893.^*^ 
Along the middle and upper thirds of the last volution the shell 
is ornamented by strong revolving ridges, usually 5 in number; 
revolving striae also are present, but usually these are faint, are 
close together, and occur on the ridges as well as on intermediate 
parts of the shell. Along the upper half of the lower third of the 
last volution there are additional faint revolving striae; along the 
lower half of this third, only the transverse striae usually are 
present. 
The third revolving ridge from the top of the last volution 
usually is located slightly above mid-height of this volution, and 
the other two ridges are so placed between the third volution 
and the suture above that the width of the intermediate concave 
spaces decreases only moderately in ascending order. The 
fourth revolving ridge occurs at an interval considerably shorter 
than that above the third ridge, and is distinctly less conspicuous. 
The fifth revolving ridge occurs at a shorter interval than any 
of the preceding ridges, and is distinctly less conspicuous than 
the fourth ridge. 
35 Idem: pi. 78, figs. 35, 36, 37. 
35 Foerste, A. F., Fossils of the Clinton Group in Ohio and Indiana: Geol. Surv. 
Ohio, Pal. vol. 7, 1893, pi. 30, fig. 15. 
