, 
7 PYRAMIDULA RUPESTRIS. 
shells, when within the matrix, always possess before exclusion about a 
whorl-and-a-half completely formed, are depressed in shape, of a dull-horn 
colour, and immediately at birth are quite able to forage for themselves. 
M. Gassies has, however, recorded the deposition during May of about 
thirty very small, round, yellowish- opaline eggs by this species, but this 
statement has not been confirmed and may well be attributed to some 
error of observation. 
Habits and Habitat.—VP. rupestris is a mollusk said to secrete an 
abundant mucus when crawling, but is sluggish and inert during the day, 
though becoming more active on the approach of evening or after rain. 
It is a true rock-snail and displays a marked preference for calcareous 
rocks, though by no means confined to them, as it is occasionally found 
on schists, granite and felspathic rocks on the continent, and on millstone 
orit, sandstones, quartzose conglomerate, slate, etc., in this country. 
It is very gregarious, living in numerous colonies, adhering during the 
day by means of a thin membranous epiphragm to the walls of buildings, 
ete., or to bare and bleak rock surfaces, fully exposed to the hot summer 
sun and all other climatic vicissitudes, a mode of life which has been 
regarded as a probable cause of the white and bleached appearance of 
the upper whorls of the shell. In this country, it however more often lives 
in the crevices of rocks, on the tops of walls and beneath loose stones, 
among the refuse in old quarries, etc., usually frequenting dry places 
more or less lofty and exposed, attaiming in the Pyrenees to the zone of 
which the rhododendron is characteristic, at an elevation of 5,000 to 6,500 
feet, and on the Pic du Midi reaching 9,000 feet. It has also been found 
by Mr. Edward Collier at an altitude of over 7,000 feet in the Valais, and 
by Dr. Cavanna at over 9,000 feet in Abruzzi. 
Geological Distribution.—PLeEtsrocenr.—Found by Mr. Blackmore 
in the brick-earth of Fisherton near Salisbury in South Wilts. 
Ho.ocenz.—P. rupestris is recorded by Kennard and Warren as found 
in a carbonaceous silt of probably Roman age, disclosed by excavations in 
‘Tooley street, Bermondsey, Surrey. 
Tn Denmark, the specimens recorded by Elberling from the calcareous 
tufa of Neder Knaberup in Ribe Stift, Jutland, have been shown by Dr. 
A. C. Johansen to be Acanthinula aculeata. 
Variation.—This species displays a great difference in form, ranging 
from an almost planorbular spire to a greatly elevated form with almost 
dislocated whorls, which has its metropolis in the Isles of the Agean Nea. 
According to Reeve, there is a characteristic analogue very similar in 
habit and character in Helix suxicola, a native of Cuba and Texas. 
Var. umbilicata Montagu. 
Helix umbilicata Montagu, Test. Brit., 1803, p. 434, pl. 13, f. 
Helix saxatilis Hartmann, Syst. Gast., "1821, p. 52. 
Helix spirula Villa, Disp. Conch., 1841, p- 56. 
Helix rupestris var. convexa Menke, Syn. Moll., 1830, p. 10. 
Helix rupestris var. subdepressa Goupil, Moll. Sarthe, 1838, p. 17. 
Helix rupestris var. depressa Westerlund, Fauna Eur., etc., 1876, p- 38. 
SHELL with spire only slightly elevated ; 
UMBILICUS more open. >» 
This, the depressed form of the species, is Ss, 
more especially prevalent in the north of Europe, 
the bulk of the British specimens probably being é; : ; i 
lic. 228.—P. rufestris v. umbilicata 
referable to it; the spire becoming more elevated GE eteiecee nal otlescse 
as the southern range increases. (after Bourguignat). 
