= jhiey S 
Figure 9, - Method of measuring 
shell andumbilicus diameters, (a); 
last whorl not descending in front, 
that is, not deflected, (b); last 
whorl descending infront, that is, 
deflected, (c). 

SYSTEMATIC ACCOUNT OF 
ECONOMICALLY IMPORTANT SNAILS AND SLUGS 
I LAND SNAILS 
Subclass PROSOBRANCHIATA 
Order ARCHEOGASTROPODA 
Family HELICINIDAE 
This is a primitive, mainly tropical family of land operculates. The shells 
are all imperforate, the umbilical region occupied by a callous pad. One 
species has been intercepted by quarantine inspectors. 
Helicina zephyrina Duclos 
Plate I, J 
This species has athick shell, rather high spire, flat- sided whorls with non- 
impressed sutures, and a roundly lunate aperture with reflected lip. Adult 
shells measure 12-15mm., in diameter. The color is pale yellow, usually 
with one reddish-brown spiral color band. The operculum is concentric. 
Distribution; Mexico to Nicaragua, 

