96 GEOLOGICAL SURVEY OF THE TERRITORIES. 
by the crossing of the varices by about five revolving raised lines which 
are distinct upon, but hardly appear between, the varices. The row of 
tubercles that mark the larger volutions begins by the gradual enlarge- 
ment of the crenulations of the second revolving line forward of the 
suture. The other revolving lines of the smaller volutions are con- 
tinued upon all the larger ones, but upon the latter they become more 
continuous and less distinctly crenulated ; and the two lines upon the 
distal side of the row of tubercles are usually obsolete upon the last two 
volutions. Besides the three revolving lines upon the proximal side of 
the row of tubercles before mentioned, the last volution shows upon its 
proximal side four or five other somewhat stronger ones, which, in the 
volutions of the spire, are successively covered by the orowth of the 
Shell. Lines of growth rather distinct; suture linear; columella flexed ; 
outer lip having a broad shallow notch, the retreating angle of which is 
opposite the row of tubercles; anterior portion of the lip moderately ex- 
tended and abruptly rounded to the columella. 
The length of a full-grown example, when entire, was probably not 
less than 100 millimeters; diameter of the last volution of the largest 
examples in the collection, 22 millimeters. 
This description is drawn mainly from my type specimens of M. 
lavunda, because they are much more perfect than Mr. Meek’s types are, 
and more perfect than any others yet discovered. In its aspect and 
ornamentation this species is so much like an Old World Melania that 
I prefer to assign it to that genus rather than to Goniobasis, with some 
forms of which it agrees in general characteristics. 
Position and locality.—Mr. Meek’s types were discovered in the upper 
strata of the Laramie Group at Black Buttes Station, Union Pacific 
Railroad, Wyoming. Examples of it were also obtained by me from 
very near the base of the group at Danforth Hills, near White River 
Indian Agency, White River Valley, Northwestern Colorado. The types 
used in its description, under the name of I/. larunda, were found in the 
valley of Crow Creek, Northern Colorado; and it has also been found 
at other places east of the Rocky Mountains in that State, 
Genus PYRGULIFERA* Meek. 
- PYRGULIFERA HUMEROSA Meek. 
The types of this species, which are also the types of the genus, were 
obtained from the Bear River series of Laramie strata, near the mouth 
of Sulphur Creek, Bear River Valley, Wyoming, in which district it is 
one of the most abundant and characteristic species of that series. It 
is described and figured in vol. iv, U.S. Geol. Sur. 40th Parallel (King), 
p. 176, pl. xvii, figs. 19 and 19a; and also in Captain Simpson’s Rep. 
Great Basin of Utah, p. 363, pl. 5, fig. 6a, b, and e. 
Genus CASSIOPELLA White. 
This genus was proposed in Bulletin U. 8. Geological Survey of the 
Territories, vol. iii, p. 606 (1877), to include the species first published 
under the name Letoplax ? turricula, in Powell’s Report Geology of the 
Uinta Mountains, p. 133. The diagnosis is also given here, because it 
is at present known only in strata of the Laramie Group. 
* For diagnosis of this genus, see vol. iv, U.S. Geol. Sur, 40th Parallel (King), p. 176. 
