GASTROPODA. 1059 
Cyclonema mediale.] 
distinguished from the typical form of the species,as above described, by having much finer surface mark - 
ings and the outer surface of the whorls almost constantly concave. The undulations of the surface, 
though occurring more commonly in this form than in any other, are not considered of much importance. 
As the more delicately sculptured variety deserves some recognition we propose to retain Mr. James’ name 
in a reduced sense for it, so it may be known hereafter as C. bilix var. fluctuatum. 
Meek’s C. bilix var. lata (Pal. Ohio, vol. i, p. 152) seems to rest on nothing more than an unusually 
depressed and somewhat abnormally coiled old shell of the typical form of the species. What he calls the 
typical form of the species is something quite different, being one of the forms of our C. mediale, while the 
high shell represented by his fig. 5g on plate XIII, which is the type of Miller’s var. conicwm, really belongs to 
the species as restricted by us. The spire in the last being higher than usual, the name conicum might 
be retained for it, but after an exhaustive study of a large number of specimens we are forced to the con- 
viction that the relative hight of the spire is a very unreliable character, each species and variety exhib- 
iting great variability in this respect. The form of the whorls is a better character, but of all the surface 
markings have served us best in separating the various species. : 
In the great confusion prevailing among collectors and authors concerning the species of Cyclonema 
occurring in the region about Cincinnati, we have found it no small task to select the particular form 
which has the best right to bear Conrad’s original name, bilix. The significant points about Conrad’s 
brief description are: (1) that the sides of the volutions are ‘‘suddenly contracted at the suture,” (2) the 
periphery is abruptly rounded, (3) the base flattened and (4) the locality, Richmond, Indiana.* 
We have a number of good specimens (about sixty, exclusive of an even greater number of the var 
Siuctuatum) from Richmond and Versailles in Indiana, and localities in Ohio exposing equivalent horizons, 
agreeing in all essential respects with the specimen illustrated on plate LX XVIII, and which, to the best 
of our knowledge, are of the same species as the one figured by Conrad. A rare variety with more convex 
whorls occurs in the Lorraine group at Cincinnati, but this is not the same as either of the two from that 
locality which have been sent to all parts of the world as C. bilix. The typical form of the species was lost 
sight of and the more easily obtained Cincinnati forms, which careless or interested observers had said 
were the same, took its place. Excepting the variety mentioned, C. bilix is restricted to the Richmond 
group and, therefore, does not occur at Cincinnati. 
We cannot agree with the practices of certain paleontologists who, either because they are incapable 
of separating the forms, or unwilling to take the trouble, would have us classify all the Cyclonema of the 
Cincinnati aud Trenton periods as one species. The following forms are as good ‘‘species” as any, afd as 
each represents a recognizable and sufficiently permanent stage in the evolution of the genus, each with 
its own set of varieties or mutations, they deserve the notice of the systematist. The more experienced 
and careful collectors long ago separated the common forms, not only because they were different but 
because they found them at different horizons. 
Formation and locality.—Richmond group, Richmond, Versailles, and Madison, Indiana; Oxford 
Waynesville, Blanchester and numerous other points in Ohio. Fragments apparently of this species were 
seen at Sterling and Savannah, Illinois, and there is no reason known why it may not occur also in 
southern Minnesota. 
Collection.—E. O. Ulrich. 
CYcLONEMA MEDIALE, 7. sp. (Ulrich.) 
PLATE LXXVIII, FIGS. 29 and 30. 
Cyclonema bilix (part.) HALL, MEEK and other authors; not CONRAD. 
Distinguished from C. bilig Conrad, by its more ventricose whorls and stronger revolving caring. 
The under side of the whorls is fuller and the outer side (Seen in the spire) is always distinctly and 
uniformly convex, there being no sign of a shoulder at the suture, nor of the median concavity, both of 
*The original] description reads as follows:— 
P. bilix, Pl. xvi, fig. 10.—Spire conical; volutions four; sides subrectilinear at base, suddenly contracted at the suture; 
surface with spiral raised strizw alternated in size; large volution abruptly rounded in its greatest circumference, base 
flattened and striated. 
Locality,—Richmond, Indiana, in limestone of the age of the rocks of Salmon River series, New York, Lower Silurian 
