THE SMALLER SEA-SHELES 193 
cidea incisa,) belongs to southern waters, and is not 
common. The shell has strong, rounded, trans- 
verse ridges, which give the spire the appearance 
of being chopped full of holes. The color is white, 
with cross stripes of brown, and its length is an 
inch and a quarter. 
Figure 199 
gives an excel- 
lent idea of a 
rare shell 
named Trophon 
triangulatus, 
Cpr., the Three- 
cornered ‘'T'ro- 
phon. The shell 
is quite large, 
but is of hght 
weight, owing to 
the extreme 
thinness of the 
L varices. It is 
Fig. 199 reddish brown 
in color though nearly white internally. When ex- 
amined closely it seems to be almost wholly made 
up of wings, and one wonders somewhat where the 
animal found internal space enough to carry on 
business. The original young specimen from 
which the species was named was dredged from the 
vicinity of Catalina Island, and was less than half 
an inch long. Adult specimens of the size of the 
cut have recently been dredged in considerable 
numbers in the vicinity of San Pedro, and a few 
have been found on the shore. 
