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IDENTIFICATION 
Since the main purpose of this publication is identification of snails and 
slugs, it will be necessary to go into some detail on characters to be looked 
for and used in making species determinations. Many of these characters 
are illustrated in figures 2 to 9. Necessary equipment for identification in- 
cludes, at the most, a 10X hand lens, 
The size and general form of the shell are important in recognizing snails. 
Their shape may take many forms, from very elongate (fig. 8a, to globose 
(fig. 8b), depressed ( fig. 8h), and discoidal (fig. 8c). It may be either 
higher than wide, or wider than high. Its coils may turn in either a left or 
right hand direction (fig. 5), be round, angular (figs. 8p, q), or flattened, 
and have shallow, impressed, or crenulated sutures (figs. 8j, k, 1). 
The shell may have few or many whorls (fig. 8g illustrates how they are 
counted), may lack an opening (umbilicus) in its base, or may have either 
a narrow or wide one (figs. 8z, aa, ab). Its columella, or central axial 
column, may be twisted or straight, and may or may not end abruptly (figs. 
8m, n). Its outer lip may be straight or variously curved (figs. 8d, e, f), 
and is sometimes turned back, or reflected (figs. 8h, i). 
The surface of the shell may be marked, that is, colored or sculptured, in 
various ways (figs. 4, 6), or may be simply white and smooth, The outline 
of the aperture, due to the shape and relation of the whorls to each other, 
may take many forms, the more common ones shown in figs. 8r to y. The 
aperture may or may not be closed by an operculum (fig. 2) which itself 
has important characters. The operculum may be round, oval, or spindle- 
shaped, and concentric, paucispiral, or multispiral, depending on the way 
in which it is formed (figs. 8ac, ad, ae, af). 
In the slugs (fig. 7), the general size, shape and contour of the body, and 
relative size of the mantle are important. Other characters used in their 
identification are: The position of the breathing pore, and the presence or 
absence of a groove in the mantle; the color, pigment patterns, and texture 
of the skin; the presence, absence, or relative size of a sharp ridge, or 
keel, on the back; the relative size of the neck; the presence or absence of 
a caudal mucous pore; the relative development of the suprapedal groove; 
and the color of the mucus. 
