192 WEST AMERICAN SHELLS 
or gray, though the outside is often very dingy. 
The picture represents a good sized specimen, 
though it sometimes grows considerably larger. 
This species loves warm water too well to migrate 
far to the north. 
Figure 198 introduces us to 
another southern shell, Mzarex 
nuttalla, Conr., Nuttall’s Mu- 
rex, (Cerostoma nuttalli). If 
you examine a full grown shell 
of this species you will find a 
sharp tooth, or horn, near the 
base of the outer lip. Some 
young specimens have no horn, 
and they have an open canal 
instead of a closed one.  Al- 
lowance must always be made 
for the age and development Hie 
of the specimen. The shell of this species is about 
two inches long, and is of a dingy white color, 
somewhat marked with brown. On each whorl are 
three distinet varices, with rounded knobs be- 
tween them. 
Murex foliatus, Gmel., the Leafy Murex, which 
is thought by some to be but a variety of the last 
species, has a larger shell which is very conspicu- 
ously marked by its three broad, wing-like vari- 
ces, which appear to be made up of overlapping 
plates, like shingles on the roof of a house. A 
magnificent specimen, dredged near Monterey and 
given to me by Mr. J. K. Oliver of that city, meas- 
ures 87mm. in length, and 63mm. in breadth. 
Murex incisus, Brod., the Incised Murex, (Muri- 
