THE 
SHELL COLLECTOR'S 
HANDBOOK FOR THE FIELD. 
CHAPTER I. 
THE ANATOMY OF A SNAIL. 
Tue SHELL.—The shell of a Gasteropod is a cone 
with the apex more or less oblique. It may be 
globose, auriculate, oval, ovoidal, lenticular, pyriform, 
ulate, pyramidal, lanceolate, discoid, trochoid, turbi- 
nated, auriculate or turretted. Generally it is coiled 
round a central axis or columella, each coil being a 
whorl, and the shell being then wniz- or multe-whorled. 
The columella sometimes opens to the exterior by a 
foramen (wmbilicus) which may be closed by a shelly 
deposit or wmbilical callus. The line of junction 
between successive whorls is the sutwre, and the apex, 
or oldest part of the shell, the nucleus. The last 
whorl has the name of body whorl, and that portion 
of it which overlaps the columella is known as the 
‘columellar lobe The aperture of the body whorl is 
B 2 
