ig) 
1903.] STANTON—MOLLUSCAN FAUNULE. 19 
humerosa Meek, and the genus to which it belongs was not known 
to occur in America outside of the Bear River formation until a 
few years ago, when a species apparently referable to it was de- 
scribed from the Dakota of Nebraska, and another undescribed 
species is now known from the same formation in Kansas. This 
fact is an additional indication that the Bear River and Dakota are 
of nearly the same age. 
It is worthy of note that the Bear River fauna includes an Ostrea, 
which proves that the formation was deposited at or near sea level, 
and that the waters occasionally became brackish, at least locally. 
The geographic distribution of the older marine formations makes 
this occurrence of Ostrea still another reason for considering the 
Bear River an Upper Cretaceous formation. 
The six species of invertebrates from near Harlowton will be 
described on succeeding’ pages under the following names: 
Onio farri. 
Cnio douglasst. 
Campeloma harlowtonensis. 
Viviparus montanaensts. 
Gontobasis ? ortmanni. 
Goniobasts ? silberlingt. 
These are all new specific names, and it will be necessary to 
depend on the known range of the species that appear to be most 
closely related in attempting to determine the age of the beds from 
which they came. 
Two of the species, Unio douglasst and Campeloma harlowtonensts, 
have their nearest relatives in the Bear River formation. Unio 
douglasst is of the same general type as U. vetustus Meek and has 
very similar beak sculpture, though it differs considerably in out- 
line and proportions. Campeloma harlowtonensis resembles C. 
macrospira Meek so closely that it is difficult to separate them. 
Viviparus montanaensis, as has already been stated, is closely 
related to V. gé/ii M and H., which has been doubtfully referred to 
the Jurassic. 
The other species of Unio is of modern type, but apparently not 
very closely related to any known fossil species, while the two 
forms that are here referred to Goniobasis have a very modern 
aspect, suggesting Upper Cretaceous rather than older types. 
Although the evidence is not fully convincing, the indications are 
that this fresh-water horizon near Harlowton is not far from the hori- 
