HOMING. 
The ability of tlie Helices, in course of ages, to excavate these 
tunnels can scarcely be (inestioned, as, in addition to their demons- 
trated power to abrade limestone and chalk with their odontoidiores, 
]\I. Bonchard-Chantereux has aftirnied from actual experiment that 
their mucoitl secretions exhibited a distinctly atdd reaction, testified 
by the reddening of litmus paper, and would, therefore, tend to dis- 
solve the rock and thus facilitate the process of the excavation. 
I’robably, however, the movements of the snails within the cavities 
have been a chief cause of their excavation, the wearing power of 
the friction of the foot being clearly demonstrated by the worn margins 
of the cavities, and by the sunken tracks leading thereto, worn away 
in the rocks by the })assage to and fro of the countless generations of 
snails which have for untold ages sought their shelter. 
These rock galleries or other permanent shelters, regularly resorted 
to hy snails as resting places after their crepuscular or nocturnal 
rambles, imply the })osses,sion of a sense of direction, or what may be 
termed orientation, in those si)ecies possessing regular abodes; this 
perce|ition or recognition of hjcality may be due to the delicacy of 
their olfactory .sense, and has been distingui.shed as the faculty of 
homing. 
This Homing jiower has been e.specially observed in Helix axpersd, 
though several other of our terrestrial species have been undeniably 
demonstrated to also ikjs.scss settled places of abode or homes to which 
they regularly return, yet there are doubtless many others which 
have no settled habitation, but conceal tbcmselves alone or in com- 
pany beneath any suitable .shelter which may liappen to ho convenient 
to their fooil. 
The inter-tidal peregrinations of the marine limpet ami its unfailing 
return to the precise spot ni)on which it is in the habit of resting, 
tirst altracted attention to this subject, and it has been demonstrated 
that their track when carefully Ibllowed almost invariably describes a 
double looi) winch may he likeneil to a variably proportioned figure of 
8, and though this peculiarity is not shared by every .s^jecies, yet the 
jiath, followed by .some of our terrestrial homing .snails, during their 
foraging ox])cditinn.s, have been ob.served to exhibit or de.scrihe the 
same remarkaltle lignre. 
Helix ((njirrsd is particularly noticeable tor its love of home and 
for the exertions it will make to regain its shelter, having been 
oljserved to traverse with great lahonr broad dusty roads or climb 
