10 
Viviparus tasgina sp. nov. 
Plate III, figure 5 
This species is midway in development between V. nidaga of the 
Belly River formation and V. crickmayi of the Willow Creek and Edmonton 
formations. This is well shown in the character of the shoulder on the 
upper part of the whorls. This shoulder, which is lacking in V. nidaga^ 
is always present in V, tasgina, but never so well defined as in V. crickmayi. 
The three species are similar in the general shape of the shell and in the 
character of the apex and spiral whorls. 
V. tasgina sometimes attains large sizes, the largest specimen found 
measuring 51 mm. in length, and others reach lengths of 33 and 40 mm. 
The increase of the apical angle with age, which was seen many times 
during the course of the present study, is excellently illustrated by V. 
tasgina, and it was noticed that the coarseness of the growth lines also 
increased with age. In the larger specimens there is a tendency for the 
whorl above the body whorl to be more elongated in the general direction 
of the axis of the shell than the younger specimens. 
The species is rather rare in the Edmonton formation and one specimen 
from the St. Mary River formation was doubtfully referred to it. The 
specific name means “policeman'’ in Sarcee Indian. 
Dimensions of Type. Length, 51 mm.; breadth, 42 mm.; apical angle, 
53 degrees. 
Campeloma veivla tenuis var. nov. 
Plate III, figure 4 
The forms found in Alberta referable to Campeloma veiula Meek^ 
are highly variable, ranging from short, stout forms with apical angles 
of 50 degrees to forms with elevated spires and apical angles of 30 degrees. 
They are abundant in the Foremost member of the Belly River formation. 
The more slender forms have been separated in the paper under a new 
varietal name C. tenuis. Several of the specimens show distinctly the 
revolving strije characteristic of C. multilineata and there is no doubt 
that the two species are very closely related. These stria? are very often 
present on the upper and lower parts of the whorl, but absent from the 
middle of the whorl. Occasionally, however, they are present over the 
whole whorl. The forms identified as C. multilineata by Whiteaves from 
the Belly River formation should be referred to this species. 
It was found on examining the collection of C. vetula in the museum 
of the Geological Survey in Washington that the forms were stouter than 
the major part of the Canadian individuals. These latter slender forms 
have hence been separated, but as a new variety. 
By a gradual flattening of the whorls and by the gradual appearance 
of an angulation at the base of the body whorl, C. vetula tenuis passes 
into C. praecursa. 
Dimensions of Type. Length, 18 mm.; width, 11 mm.; apical angle, 
47 degrees. 
iMeek: U.S. Geol. Surv., Terr., vol. 9, p. 678, PI. 42, figs, 14a, b (1876). 
