144 WEST AMERICAN SHELLS 
sacti, in river drift, and similar positions. The 
names of the chief species, with brief references, 
will be given in the List, but the shells are so very 
small that few of them will be fully deseribed. 
Holospira  arizonénsis, 
Stearns, the Arizona 
Pupa, is shown in Figure 
122. The shell is really 
but half an inch long; the 
figure, however, brings 
out the details of its strue- 
ture. In color it varies 
from dingy white to pale 
horn. It was collected at 
Dos Cabezas, Arizona. 
Some of the species of 
Fig. 122, x 3 (*) 
the old genus Pupa are now known as Bifidaria, 
among which we may notice Bifidaria armifera, 
Say, the Armored Pupa. This species is found all 
through the East, also it has been collected in New 
Mexico. It is relatively quite large, being from 
2 to 4mm. in length. It resembles Figure 121, but 
has six or seven whorls, and the aperture is al- 
most filled up with projecting teeth. 
Figure 123 
Fig. 123 
gives a view of the shell of 
Succmea ovalis, var. hayden, W. G. B., 
Hayden’s Amber-snail. 
may be said that the Amber-snails are 
rather small mollusks, which love moist- 
ure, though they do not often enter the 
In general it 
water. The yellowish shell of this species 
is long, thin, and few-whorled. 
The aperture is 
very large, and from its base you can look inside 
