WHITE. ] LARAMIE FOSSILS. 103 
This is one of the few forms found in the strata of the Laramie Group, 
the only known closely-allied species to which are associated with marine 
species only. 
Its immediate associates are Ostrea and Anomia in abundance, and a 
few imperfect examples of Melania ? insculpta. Of itself, this species is 
suggestive of a marine habitat, but it is probable that, like the Nuculana 
and Awinea described in this article, it survived, without generic 
change, in thé freshening waters of the Laramie period. This supposi- 
tion is not at all an improbable one, as there is sufficient evidence, aside 
from the presence of these shells themselves, that the water in which 
they lived was in a considerable degree saline. 
Position and locality Bitter Creek series of the Laramie Group, two 
miles west of the Point of Rocks Station, Union Pacific Railroad, Wyo- 
ming. 
ODONTOBASIS? FORMOSA White. 
Plate 28, fig. 7a. 
Goniobasis? formosa White, 1878, Bull. U. 8. Geol. Sur. Terr., vol. iv, p. 718. 
Shell rather small; spire equal to about one-half the entire length; 
volutions about six; the last one inflated, and those of the spire moder- 
ately convex; the distal part of each volution somewhat shouldered, and 
marked at that part by numerous small longitudinal varices that be- 
come obsolete towards the’ proximal part of the last volution; these 
yarices are not more distinct upon the body volution than upon those 
of the spire; upon the latter spire there is also a small revolving fur- 
row near to and upon the distal side of the suture, giving those volu- 
tions a slightly constricted aspect, but which furrow seems not to extend 
to the body volution. Surface marked only by lines of growth, with 
the exceptions already mentioned, and that of some faint revolving lines 
upon the proximal side of the body volution, near the columella. 
Length, 12 millimeters; breadth of body volution, 7 millimeters. 
Only one example of this species has been found, and this is a some- 
what distorted natural cast, from the reddish shales of the Laramie 
Group, near its base. Neither the aperture nor the extremity of the 
beak is shown in the specimen, and I am not entirely satisfied that it 
belongs to the genus Odontobasis. It plainly does not belong to any 
described form, and it has the general aspect of a marine shell. I there- 
fore refer it, provisionally, to that genus, because it approaches it more 
nearly in its characteristics than any other known genus which is likely 
to exist in the Laramie Group. With this view of its affinities it is 
interesting as adding another form to those found in the Laramie Group, ° 
which are regarded as marine types. 
Position and locality—Laramie Group, about 400 feet above its base, 
Danforth Hills, near White River Indian Agency, Northwestern Colorado. 
