HELIX PISANA. ote 
ment of an iridescent mucus, which imparts to them a somewhat glossy 
appearance ; they are laid about a week after pairing, the period of ovi- 
position, according to Dupuy, extending from the end of summer to as late 
as Noy. 25th: the eges are usually about sixty in number, but said to be 
deposited at three different times, just beneath the surface of the ground, 
probably beneath stones and at the roots of shrubs or plants; they hatch 
in about twenty days, and emerge from the ground bearing a shell nearly 
two mill. in diameter. 
In the course of its growth the young shell displays some very striking 
modifications in its aspect, and Dr. Germain in the south of France and 
M. Girard in Portugal have studied the various phases of development they 
undergo, recording that the young are hatched towards the end of autumn, 
slowly i increasing In size throughout the winter and following spring until 
the time of wstivation causes a cessation of growth; at this period the shell, 
which is usually whitish and relatively thick, has attained three to four 
whorls, and shows affinity in form with immature /7. lapicida and with the 
adults of Helix explanata, in having a subtetragonal mouth, a very flat 
spire and an exceedingly deep and convex base, separated by a very acute 
and distinct keel. Before its summer siesta, the animal strengthens the 
aperture of its shell and secretes a strong and calciferous epiphragm, by 
which it affixes its shell securely to fully exposed stone walls or stems of 
plants and trees, particularly favouring those of the Broom (Siruthamnus 
scoparius l.), but many die during this period, which seems a very critical 
one in its life’s history. 
The young shell in this condition is found throughout the range of the 
species, and was long ago named Carocolla yam “FG. 419.—-Carocolla cine 
cine by Klett; it is also probably the <a  Giekihe Gataan: 
Helix wstivalis of Bourguignat, and more “ (Mus. Hist. Nat. Paris). 
recently has been distinguished as /elix catocyphia inerme by Girard. 
The Helix hyperplate of Servain, which was founded on specimens dis- 
covered in the [berian peninsula, and has also been found plentifully on 
the dunes of 'labarka and in the region of Ain-Draham, ‘unis, by M. de 
Kerville, was also evidently established on immature shells whose growth 
has been arrested at a somewhat later stage of life than that of the 
Cutocyphia inerme, as the body whorl is described as only keeled at its 
origin, the periphery rounded towards the aperture, the spire more convex, 
and the peristome thicker; while the 7heba leucostoma Risso is also said 
to be an immature stage of the species. 
At this stage of its development, but only in hot and arid littoral situa- 
tious on calcareous, basaltic, or sandy and possibly alkaline soils, a 
cretaceous tubercle may be occasionally developed which is usually placed 
on the middle of the parietal wall, but occasionally at the base of the 
columella or even upon the outer lip. Fic. 420. 
This peculiar juvenile and probably te Helix catocyphia Bours. 
atavistic form, which differs so strikingly “—=S MEG e Gude, 
from the adult, was regarded as a distinct lieeOly He Besr 
species, and named Helix catocyphia by Bourguignat, and placed by Locard 
in the genus Tropidocochlis with Helix explunate, while M. Charreyre 
actually regarded it as a variety of that species; M. Girard has, however, 
demonstrated that it is merely a juvenile and undeveloped form of //e//x 
pisana with scarcely a perceptible trace of the reproductive organs, which 
occupy so large a part of the body cavity of adults. 
