PREFACE 
This publication is presented as an aid to Plant Quarantine officials 
whose work at the various inspection stations often calls for know- 
ledge and identification of snails, which, if introduced into the United 
States, may become agricultural pests. Some are implicated as dis- 
ease carriers. Because of our increasing knowledge of the role 
they play in the transmission of communicable diseases, the eco- 
nomic lossesto gardens and orchards caused by foreignland snails, 
and the widely publicized depredations of the giant African snails 
in the Pacific, the importance of preventing entry of such undesir- 
able alien pests is now becoming fully appreciated. 
Included in this publication are species native toforeigncountries, 
snails that have become pests in the past, species commonly en- 
countered at inspection stations, andthe more important humanpar- 
asite vectors. To aid the worker who has had no training in the field 
of mollusks, the economic significance, control, habits, ecology of 
snails and slugs, and a minimum of information onthe groups as a 
whole are presented. Following the identification of the snails and 
the section on species descriptions is a key for the identification of 
them. Aglossary, selected references, and index are also included. 
Grateful acknowledgment is made to Harold A, Rehder, U. S. Na- 
tional Museum, and Henry vanderSchalie, Museum of Zoology, Uni- 
versity of Michigan, for advice and use of their facilities; and to 
William L. Brudon and Betty Anthony, Museum of Zoology, Univer- 
sity of Michigan, and Arthur Cushman, U. S. Department of Agri- 
culture, for their skillful work in producing the plates. A note of 
special gratitude goes to J. P. E. Morrison, U. S. National Muse- 
um, whose constant advice, helpful criticism, and unfailing support 
have contributed so greatly tothe successful completionof this pub- 
lication. 
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