XEROPHILA VIRGATA. 151 
It is found, though not abundantly, at ‘thrush stones,” indicating it as 
occasionally eaten by the thrushes, as it is by blackbirds also. 
Perhaps the sheep are the greatest destroyers of this species, which is 
said to be sought for by them, as the sheep have been noticed to frequent 
and graze at those places where the shells are most plentiful ; this diet is 
believed to give to the South Down mutton its peculiar and prized flavour. 
Mice are also stated to make it an article of food at Northampton, 
according to Mr. C. E. Wright. 
Melinda, a group of flat-bodied, blue dipterous flies which in their 
larval stage are recorded as parasitic upon, devouring and eventually 
destroying XV. virgata and other species. 
M. cognata Robineau-Desvoidy, which is common about Cambridge, deposits its 
eggs from May to August, in or near the respiratory orifice of XY. virgata, to which 
species it is apparently restricted, as H. hortensis, X. itala, and other species, 
plentiful around, were not infested. The larvz on hatching bore into the kidney, 
feeding upon its substance and juices, and afterwards devouring the liver and other 
organs. Before the larva is full grown, the snail dies, becomes a decomposing liquid 
mass, and forms the final meal of the larva, after which it forsakes the shell of its 
victim, and burrows in the earth to pupate, the fly emerging in about a fortnight, 
the whole life cyele oceupying about a month. 
Other larvze of the same species (or of MW. gentilis Robineau-Desvoidy, an allied 
species, which have been obtained by Dr. E. W. Bowell from X. virgata) may for a 
time exist in the same shell, but they are eventually destroyed and fed upon by the 
survivor, as only one larvee attains maturity in each shell. 
The Melinda larvie are, however, themselves liable to be destroyed not only by 
the larvee of certain Ichneumon flies, which are especially parasitic upon them, 
but also by the sarcophagous and possibly saprophagous larvae of Sarcophaga 
crassimaryo Pand, a dipteron which Dr. Keilen believes invades and devours the 
remains of any snail which has been previously parasitized and killed by the 
Melinde. 
Geological Distribution.—The maps showing the fossil distribution 
of this species as known to me, will show how few are the observations that 
have been made upon this aspect of the subject, and will certainly 
emphasize the desirability of caution in drawing any final conclusions 
from such scattered data, if at all conflicting with the more numerous 
and palpable evidences presented by geographical distribution. 
It has been remarked by Kennard and Woodward that the large coarsely 
striated form of XV. wrgatw prevailing in the south-east of England and on 
the opposite continental coast is quite unrepresented in Ireland, the recent 
shells as well as those of the Irish deposits being identical with those of 
the west of England. 
ENGLAND. 
PLEISTOCENF.—In Kent East, it is recorded from the fluviatile deposits at 
Faversham by Prof. Morris. 
In Essex South, it is cited from the drift in Sam Green’s pit, Ilford, by Mr. J. P. 
Johnson ; and is also recorded from the freshwater marls of Clacton. 
In Cambridge, it is recorded from the drift at Barnwell by Mr. Johnson, and as 
common in the gravels at Barrington near Cambridge by Mrs. McKenny Hughes. 
In Worcester, it is recorded from the freshwater deposits of Cropthorne near 
Pershore by Prof. Morris. 
FOREIGN DISTRIBUTION. 
In France, Helix variabilis-antiqua is reported from beds in the Mediterranean 
basin by M. de Serres, and this species or ‘‘an analogous fossil” from the deposit 
at Dax, Landes, by M. Grateloup ; while Dr. Paul Fischer has recorded it from 
the bone-breccia bed of the cavern of Bagneres de Bigorre, Hautes Pyrénées ; 
Caziot and Maury report H. maritima var. fabroniana from the Valley of the Var, 
Alpes Maritimes ; and M. Caziot also records it from the Upper Pleistocene bone- 
breccia at Toga near Bastia, Corsica. 
