ware.) TERTIARY FOSSILS. AT 
This species very closely resembles, both in size and shape, Pupa cali- 
fornica Rowell, as figured and described by Binney and Bland in Land 
and Fresh-Water Shells of North America, part I (Smithsonian Miscel- 
laneous Collections 194), p. 239, fig. 413. These authors give the diame- 
ter of that shell as one millimeter, which is the same as that of ours; but 
they state its length ‘to be two and a half millimeters, which is one-fourth 
longer than the proportions of their figure indicate. I have never seen 
an example of that shell, but their figure (loc. cit.) probably correctly 
represents its proportions, which are therefore nearly the same as those 
of our shell. Indeed it is difficult to say, with the present knowledge 
only of our shell, wherein it differs from P. californica, but as no living 
species have been found in the strata from which the former comes, and 
as all its characteristics are not yet known, it would probably not be 
warrantable to refer it to a living species. It differs conspicuously from 
the last-described species, P. arenula, with which it is associated, and 
with which it corresponds approximately in size by being much less 
globose, and apparently in not having its aperture contracted. It has 
the aspect of the typical forms of Pupilia, and ought probably to be 
referred to that subgenus. 
Position and locality—Upper Green River Group, Henry’s Fork, Wy- 
oming, where it is associated with the following as well as with the pre- 
ceding species, and also with other pulmonate gasteropods. 
Subgenus LEUCOCHBEILA Albers. 
PupA (LEUCOCHEILA) INCOLATA White. 
Plate 19, figs. 7 a, b, and c. 
Pupa incolata White, 1876, Powell’s Rep. Geol. Uinta Mts., p. 130. 
Shell small, elongate, distinctly rimate, sides somewhat regularly ta- 
pering along the greater partof the length of the shell, but inore rapidly 
converging at the extremity to a slightly obtuse apex; volutions about 
Six; convex regularly increasing from apex to aperture, the last one not 
contracted ; suture impressed ; aperture subovate in outline, its length 
a little more than one-third that of the whole length of the shell; outer 
lip thickened, prominent, reflexed ; aperture apparently without either 
teeth or folds, but the condition of all the specimens in the collection is 
unsatisfactory in this respect. 
Length, 5 millimeters; diameter of last volition, 2 millimeters. 
This species closely resembles in size, form, and general characteris- 
tics, Pupa (Leucocheila) fallax Say, but the sides of our shell converge at 
a somewhat greater angle than they do in Say’s species, and its peri- 
stome is also more thickened and expanded. It appears to possess all 
the characteristics of the subgenus Leucocheila ; or at least it differs sub- 
generically from the typical forms of Pupa. The fact that we find two, 
and perhaps three, subgeneric forms of the Pupide in the Eocene strata 
of Western North America, is of great interest as regards the question 
of the early differention of existing types of pulmonate mollusks. 
Position and locality—Upper Green River Group, valley of Henry’s 
Fork, southward from Green River City, Wyoming, where it was found 
ae with the two preceding species, and also with Helix, Planorbis, 
C. 
