Mollusca are the second largest phylum of the animal kingdom, forming a major part of the
10 world fauna. The Gastropoda is the only class of molluscs which have successfully invaded
11 land. They are one of the most diverse groups of animals, both in shape and habit. Among
12 gastropods, land snails (subclass: Pulmonata) are one of the most numerous with almost
13 35,000 described species of the world. The present study dealt also with the chemical
14 analysis of the mucus of three common land snails, Eobania vermiculata (Müller), Theba pisana
15 (Müller) and Monacha obstructa (Montagu), and identification of the chemical compositions
16 by using GC-MS. Results revealed that several variations in composition were observed
17 between all species. Oxime, methoxy-phenyl and cyclotrisiloxane, hexamethyl were major
18 components found that in three species, the total areas detected were 86.23, 76.83 and 70.83,
19 respectively. This different composition of mucus may be due to differences from one
20 species to another; different mechanical properties (function) are influenced by external
21 factors such as temperature, humidity, light intensity, soil conditions and food supply. On
22 reviewing literature conducted on land snails of Egypt, as far as can be ascertained, most
23 studies were focused on Lower Egypt but Upper Egypt was neglected. So, the present
24 investigation was designed to fulfil this gap and to promote and enhance the studies of land
25 snails, especially those which have economic importance.