46 GEOLOGICAL SURVEY OF THE TERRITORIES. 
aperture large. Surface marked by the ordinary lines of growth, and, 
under the lens, faint, close-set, revolving striz are seen crossing the 
fine lines of growth, giving the surface a fine cancellated appearance. 
Length 11 millimeters; breadth accross the middle of the aperture 6 
millimeters. 
There areat best only a few salient specific characteristics observable in 
the shells of any species of Suecinea, but this shell may be regarded as 
distinguished from all other species with which it is in any danger of 
being confounded by its minute spire, the very abrupt spreading of the 
body volution, or rather part of a volution, from those of the spire. 
Figure 4 a, plate 19, is drawn from a gutta percha cast of a natural mould 
in fine-grained sandstone, the latter having been a little distorted by 
pressure. i 
This species.was discovered by the writer in the summer of 1875, and 
up to the present time no other fossil species of the genus Succinea has 
been discovered in North American strata. The discovery of a repre- 
sentative of this genus among the early Tertiary pulmonate mollusea is 
an interesting one; and the interest 1s increased also by the evidence 
which it affords that the subgenus Brachyspira of Pfeiffer was estab- 
lished as a subgenerie type as early, at least, as the Hocene epoch. 
Position and locality y.— Upper Green River Group, Alkah Stage Station, 
some twenty miles northward from Green River City, Wyoming, at which 
locality alone the species has yet been discovered. 
Conus PUPA amare 
PUPA ARENULA White. 
Plate 19, figs. 8 a and b. 
Pupa arenula White, 1876, Powell’s Rep. Geol. Uinta Mts., p. 131. 
Shell minute, ovate; spire obtusely rounded, its apex slightly promi- 
nent or merely convex; volutions, five or six, moderately convex; suture 
impressed; last volution contracted near the aperture; border of the 
aperture apparently reflexed, but its true shape, and the character of 
the armature, if any, of the aperture, unknown, in consequence of the 
imperfection of the specimens. 
Length, 2 millimeters ; diameter, 14 millimeters. 
This shell, in shape, size, and general aspect, closely resembles Vertigo 
ovata Say, among living Pupide. It appears, however, to be either 
Pupa proper, or referable to the subgenus Pupilla. 
Position and locality—Upper Green River Group, valley of Henry’s 
Fork, southward from Green River City, Wyoming, where it is asso- 
ciated with the two species next described, and also with Physa, Planor- 
bis, &e. 
PUPA ATAVUNCULA (sp. nov). 
Plate 19, fig 9 a. 
Shell minute, elongate subovate; the sides of the spire, for greater 
part of its length, subparallel; the distal portion of the spire, together 
with the apex, obtuse; volutions about five, convex, gradually inecreas- 
ing insize; suture impressed. Aperture unknown, but it is apparently 
not contracted. 
Length about 14 millimeters; diameter, 1 millimeter. 
