MARINE UNIVALVES 165 
mal withdrawn by a little hook or bent wire. Many 
marine mollusks may be killed readily by simply 
putting them into a dish of warm fresh water and 
leaving them for a little while. 
If only a portion of the body ean be obtained the 
shell may be put into a solution of formaldehyde 
or some other disinfectant for a time, and when 
dry the opening may be plugged with cotton, to 
which the operculum may be attached by a drop 
of glue. They will then appear as if they were 
living specimens. Much will depend upon one’s 
time and taste for this part of the preparation, 
but the thorough cleaning of the shell is indispen- 
sable, and should be attended to as soon as possi- 
ble after the specimens are gathered. 
Olivella pedroana, Conr., the Pedro Olive- 
shell, (O. baetica) Figure 152, has a more 
slender shell than that of the last species. 
The lip is thin, the spire quite tapering, 
while the color is generally brown or bluish. 
Olivéella wntorta, Cpr., the Twisted Olive-shell, 
has a small, oval shell, more compact than that of 
the last species. The spire is elevated, and the 
suture is very distinct. There is a large callus 
on the upper part of the inner lip, and there is but 
one distinct fold on the columella, instead of two, 
as in O. biplicata. There are generally more or 
less yellow stripes on the surface of the shell, the 
greater portion of which is hght colored. The 
outer hp is more curved at the base than that of the 
last species. 
Fig. 152 
