182 WEST AMERICAN SHELLS 
Liomesus canaliculatus, Dall, 
the Channeled Liomesus, is 
shown in Figure 182. It is an- 
other northerner, and its shell is 
white, with a velvety epidermis. 
Its length is 35 millimeters. 
The next genus which we will 
consider is named Nassa, a word 
which literally means a _ basket 
for taking fish. Most of the mem- 
bers of this genus have a reticu- 
lated surface, somewhat like net- 
work, or the sides of a basket. 
Our largest member of the 
genus is shown in Figure 183, 
and is named Nassa fossata, Gld., 
the Channeled Nassa. The spire 
is conical and ends in a pointed 
apex. The surface of the whole 
shell is marked with spiral and 
transverse ridges, the former of 
which appear also within the 
outer lip. The thickness of this 
lip varies much with the age of 
the animal, as does the eallus of enamel which is 
spread over the columella. This enamel, in ma- 
ture specimens, 1s of a bright orange color, and 
contrasts finely with the hght ash-color of the gen- 
eral surface of the shell. The canal is short and 
abruptly reflected, while just above it is a deep 
ditch or fossa, showing at once from what fact the 
Fig. 182 (*) 
