196 STANTON—MOLLUSCAN FAUNULE. [April 8, 
The figured type, which is of about the average adult size, gives 
-the following measurements: Height, 12 mm.; greatest breadth, 
1o mm.; height of aperture, 7 mm.; breadth of same, 5 mm. The 
collection contains about two hundred specimens, which show little 
variation except in size. Part of the specimens, supposed to be 
immature, are considerably smaller than the type. 
This species is very similar in general appearance to Viviparus 
gilli Meek and Hayden, which was described’ from beds provision- 
ally referred to the Jurassic at the head of Wind River, Wyoming, 
but it differs from the Wyoming form in being slightly smaller, and 
in having more distinctly shouldered whorls, a more oblique aper- 
ture, and with the inner lip more closely appressed to the shell and 
not so prominent. 
Locality.—Wettacombe’s ranch near Musselshell River, in the 
vicinity of Harlowton, Montana. 
ffTorizon.—Upper part of Lower Cretaceous or base of Upper 
Cretaceous. 
CAMPELOMA HARLOWTONENSIS n. sp. Pl. IV, Figs, 11, 12. 
Shell iarge, elongate subovate, consisting of about six elevated 
convex whorls, separated by a linear impressed suture; aperture 
large, ovate ; inner lip moderately thick, forming a rather heavy 
callus on the shell above and slightly reflexed below, so as to 
partly cover the small umbilical depression or chink; surface 
marked only by fine, slightly sigmoid lines of growth. 
The type, which is the largest specimen in the collection, measures 
63 mm. in height (with apex restored) and 38 mm. in greatest 
breadth; height of aperture 34 mm. and breadth of same 23 mm. 
The other figured specimen is 57 mm. in height (with apex re- 
stored), 38 mm. in breadth, and the corresponding dimensions of 
the aperture are 29 mm. and 22 mm. respectively. 
This second specimen shows other differences in the aperture 
besides its relatively greater breadth, the inner lip being thicker 
and not so closely applied to the preceding whorl above and having 
a larger umbilical depression uncovered below. These variations 
are probably all accidental, as there is distinct evidence of injury 
to the shell during the life of the animal, shown by a repaired 
break nearly parallel to the outer lip and a few millimeters from it. 
1 Palaeont. of the Upper Missouri, p. 115, Pl. V, Fig. 3, ¢, 4, Washington, 
1865. Figured also by White in Bull. No. 29 and in 7hird Ann. Rept. U.S. 
Geol. Surv, 
