50 HYGROMIA FUSCA. 
tricuspidate tooth, with a strong central cone, and quite small ectocones; the 
laterals are about 14 in number, and also tricuspidate, the ectocones being well 
developed, but the endocones are very feebly represented and gradually diminish in 
size; the marginals are more or less quadrate in shape, and characterized more 
especially by the splitting of the mesocones, by a very decided overlapping of their 
lateral margins and in a lesser degree by the division of the sinaller ectocones. 
The formula of a Huddersfield specimen collected by Mr. Lister Peace and the 
radula prepared by Rev. Prof Gwatkin is 
22 41441414412 x 95 — 5,035 teeth. 
Reproduction and Development.—No observation appears to have 
been made of the sexual congress of this species, except by Capt. Farrer, 
who, on Noy. 11th, 1905, observed individuals in conjugation at Bassen- 
thwaite ; but the function probably takes place from August till towards 
the end of the year. The eggs are laid shortly after the congress, and are 
from 30-50 in number, 1 to 13 mill. in diameter, and globular in form, 
with a thin, transparent, and opalescent envelope; they hatch in about 
twenty days, the young becoming adult during the following season. 
Habits and Habitat.— Hygromia fusca is found fairly commonly 
in districts where it occurs, living upon the sedges bordering the streams 
in moist or damp woods, and is a habitual climber, especially in the early 
autumn months, ascending the alder, beech, poplar, hazel, osier, juniper, 
mountain-ash, and other trees, feeding upon the leaves and clinging to 
their undersides. It also frequents many plants, especially the great hairy 
woodrush (Luzula sylvatica), the meadow sweet (Spera@a ulmaria), cam- 
pion (Lychnis dioica), dog mercury (Mercurialis perennis), Iris, Equisetum, 
nettles, sedges, ferns, brambles, ete., and is easily collected by shaking 
shrubs or the lower branches of trees over an umbrella. 
In France, at Mont-de-Marsan, it abounds on the bindweed in the 
hedges, as well as on the osiers and the marsh-reed. 
It is a very hardy species, and in late autumn and winter is remarkably 
active and more geophilous in habit, living amongst the decayed leaves 
and herbage. 
Though evidently feeding on a great variety of plants, Capt. Farrer finds 
that in the Lake district its favourite food is wild carrot (Daucus carota). 
M. St. Simon has recorded that he had observed 85 pulsations per 
minute of the heart of this species, but gives no details of the conditions 
under which the observation took place. 
Mr. Masefield has noticed its marvellous protective resemblance to the 
decaying seed capsule of the campion (Lychnis dioica), the thin shell 
being the exact colour of the capsule when wet, and the base being of a 
pale yellow colour exactly resembles a portion of the viscera of the snail 
as seen through the shell. 
Parasites and Enemies.—In addition to the usual Helicidian 
enemies, Mr. Evans has observed that the bank vole (Hvotomys glareolus) 
seems particularly fond of this species, as he has found an abundance of 
broken shells at the entrance of their burrows. 
Geological Distribution.—Recorded by Dr. Jeffreys as fossil in our 
Upper Tertiary formation; by Prof. Morris as found in the Mammaliferous 
Crag, at Stutton, Suffolk ; and by M. Laville, in France, from the gravels 
of Joinville-le-Pont, department of the Seine. . 
Variation.—Only two forms of 1. fusca have as yet been distinguished, 
as it 1s not a species which lends itself to a splitting-up into many forms. 
