Many gastropods, including limpets, periwinkles, and mud snails, detect and follow mucous trails. The stylommatophoran pulmonate snail Mesodon thyroidus follow conspecific trails in the field, potentially following in the direction they were laid, as has been demonstrated for other pulmonates. This study investigated whether individuals of M. thyroidus directionally follows conspecific trails, and whether substrate type or incline influences trail following. Trail following was quantified on plexiglas and glass surfaces at horizontal, vertical, and 45° inclines. On horizontal plexiglas surfaces, 36% of M. thyroidus followed a marker trail made by a conspecific (n = 11). On horizontal glass surfaces, 45% of the snails followed a marker trail (n = 20). On glass (all inclines combined) 75% of snails that followed a conspecific trail followed it in the same direction it was laid (n = 60). On plexiglas (all inclines combined) 86% of trail-following proceeded in the direction the trail was laid (n = 33). The difference in the results across the two substrates could indicate a behavioral reaction to the chemical difference of the substrates. Preliminary observations of tentacle movements and of the mucous trails indicate that previously laid trails can be detected before the foot of the following snail contacts the marker trail.