40 HYGROMIA REVELATA. 
Reproduction and Development.—Nothing is known of the details 
of the congress of this species; it is, however, believed to become adult in 
the autumn, when reproduction takes place, Dr. Brooksbank remarking that 
in its favourite haunts in West Cornwall the eggs are so abundant in late 
autumn as to betray the whereabouts of the snail. 
Food and Habits.—WH. revelatu, according to the experience of Mr. 
J. R. le B. Tomlin, is best collected in dry weather, when it may be found 
at the foot of stones and rocks which are closely edged with short thick 
grass. After rain it becomes very active, and may be found dotted over 
the grass and herbage, but is then very difficult to detect. 
It is most frequently found near the roots and beneath the foliage of 
nettles and plants of a tufted and recumbent character, beneath or amongst 
stones on the tops of cliffs or open downs, but sometimes clustered beneath 
the shade of the spreading branches of Gorse ( Ulex europeus). 
It is gregarious, and more especially congregates in hollows on slopes 
where small pieces of disintegrated rock have slipped from above and 
become piled together. 
It shows, according to Mr. Tomlin, a great partiality for a small fragrant 
wild thyme which abounds on the cliffs. Mr. Rimmer especially remarked 
that its favourite food was the leaves and roots of the sorrel (Aumewx ace- 
toselluw), about whose roots it congregates in its native resorts, and that in 
captivity it devoured that plant with apparent relish. Mr. Sikes in Seilly 
always found it at the roots of small dandelions (Taraxacum officinale). 
In this country it appears to be restricted to the vicinity of the sea, 
which does not appear to be the case in less vigorous regions, where /. 
occidentalis may be found far from maritime influences in pine woods, at 
the foot of old oaks, etc., often buried more or less deeply in the earth, but 
especially on waste land beneath tufts of Artemisia campestris. 
In winter and during persistent dry weather it is said to bury itself 
rather deeply in the earth, and in winter forms a protective epiphragm, 
which is thick, opaque, and white, and sunk somewhat within the aperture; 
but for summer estivation this protective device is usually, though not 
invariably, thin, glistening, and iridescent, with a small opaque spot, or, 
according to Dr. Jeffreys, a small round hole opposite the respiratory orifice. 
At such times it must be looked for by pulling up tufts of grass and 
turning over large stones which are sunk in the ground, or by searching 
among the roots of furze bushes or other shrubs. 
Geological Distribution.—Recorded by Mr. A. W. Stelfox in a some- 
what ancient Holocene deposit at Whitesand Bay, Cornwall. 
Variation.—The known variation of this species is very restricted, 
although several assumed species have been established which differ but 
slightly from the type. 
Profs. Hidalgo and Pilsbry regard as varieties the Helia coimbricensis 
and H. nevesiana Silva. Prof. Hidalgo also adds the H. martigenopsis of 
Servain from Lisbon and Mirando de Ebro, Helix venetorum, Helix villula, 
and Helix platylusia Bourguignat ; whilst Prof. Pilsbry adds. 1. martigena 
Fér. ; but some of these, as H. martigena Fér., are probably more closely 
allied to H. montivaga or H. ponentina. 
