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upwards. Tunnels dug on the top of pre-existing holes show a trend which is, from the very beginning, upwards.
Tunnels may be distant from or, more frequently, next to each other. In the last case, their progressive enlargement
may cause the dissolving or even collapse of dividing walls, resulting in broad cavities the outside margin of which
is circular or ellipsoidal (with a diameter from 10 to 30 cm, up to a maximum of more than 60 cm) and whose inte-
rior walls are pitted due to the remnants of each tunnel (Fig. 30b).

The snails’ rock-boring ability results fom the secretion of a H2CO3-rich mucus used to dissolve the calcium
carbonate of the limestone; residues are then removed by the radula and, according to Sacchi (1955a), also by the
rough shell surface. Mucus evaporation may cause re-deposition of calcium carbonate, giving origin to peculiar
botroidal concretions close to the tunnel opening (Fig. 30d).

Specimens also show homing behaviour. At night or on moist and rainy days the snails leave the tunnels and
crawl on calcareous cliffs or soil moving for several metres, while they return to the place they came from when it
gets drier. Sometimes they also aggregate in fissures in the rock. In field experiments in which adult animals were
marked and tracked in their natural environment, it was documented that these helicids rest in, leave and go back to
the same group of tunnels over extended periods of time, even more than one year long (personal unpublished
data).

As for these snails’ diet, Varga (1989), analyzing the contents of the digestive tract and fecal pellets of Helix
mazzullii specimens, found still recognizable plant fragments. In personal observations, we witnessed several times
specimens of the H. mazzullii complex feeding on living or dried parts of different plants occurring on the rock face
or at the rock base.

The taxa of the H. mazzullii group are strictly rupicolous (= inhabiting rocks) and possess saxicavous (= rock-
boring) abilities and thus occupy an ecological niche different from that of the closely related genera Cornu and
Cantareus whose very common and widespread species are strictly linked to the soil.

Paleontology

Fossils attributable to H. mazzullii (s. str.) were recovered at the following sites:

● near Palermo (Philippi 1836; 1844)
● Billiemi (Palermo), in bony breccias (Calcara 1845a; 1845b: as Helix retirugis)
● Monte Pellegrino (Fig. 31) and Ficarazzi (Palermo province), in post-Pliocene fossilliferous deposits (Monte-

rosato 1872; 1877; 1891)
● Monte Pellegrino, in quaternary deposits encrusting secondary rocks, including fossil deposits of rodents and

carnivores from the mountain peak (of continental origin) and the post-Pliocene detrital limestone (calcareous
arenite of marine origin) (De Gregorio 1886; 1895; 1916a; 1916b; 1927)
● Castellana (Boccadifalco, Palermo) (De Gregorio, 1886)
● near Palermo, in quaternary deposits encrusting secondary rocks of the mountains (quite frequent) (De Grego-
rio 1927)
● Pietrazzi county (Palermo), in a post-Pliocene deposit (doubtful records) beneath a marine shelly limestone
layer (De Gregorio 1927)
● Bisaquino (Palermo), in quaternary rocks (one specimen) (De Gregorio 1927)
● caves near Palermo (grotta dell’Addaura, grotta Perciata and grotta delle Vitelle), in prehistoric deposits (very
frequent), or in the surroundings of caves [grotta della Conza (Sferracavallo) and grotta del Maccagnone (Car-
ini)] (Anca 1860a; 1860b; 1867; Falconer 1868; Tricomi 1926; 1929; De Stefani 1941)
● Luparello cave (Baida, Palermo) (De Gregorio 1895; 1899: as Helix Luparellensis) (Fig. 32). Although the fos-
sil assemblages of the Luparello cave underwent considerable reworking over a long time (Burgio & Costanza
1999), H. luparellensis is, beyond any reasonable doubts, associated with the vertebrate fauna including
Elephas falconeri Busk (fossil dwarf elephant) (De Gregorio 1895; 1899; 1927). This fauna, dating back to the
Middle Pleistocene, around 550,000 years ago (Kotsakis 1979; Belluomini & Bada 1985; Bada et al. 1991;
Bonfiglio & Burgio 1992; Burgio 1998), is the richest one in endemic species of the quaternary period in Sicily
● Alcamo, Elephas falconeri complex in continental sandy limestone (locally called “travertino”) (Burgio &
Cani 1988; Abate et al. 2006) (Fig. 33)

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