MONOGRAPH 
OF THE 
LAND AND FRESHWATER MOLLUSCA 
OF THE 
BRITISH ISLES 
Puoytum MOLLUSCA Cuvier. 
Crass GASTROPODA Cuvier. 
SusB-Ciass ANIJISOPLEURA Lankester 
OrpeER EUTHYNEURA Lankester. 
Sus-Orpver STYLOMMATOPHORA A. Schmidt. 
FAMILY HELICID# Linneé. 
GENUS HYGROMTA Risso. 
(Trichia, Hartmann; Fruticicola, Held ; Capillaria, Honigmann; Bradybana, Beck). 
Antoine A660 
HE term /Hygromia (vypés, moist or damp) 
aptly designates the present genus, which 
is especially characteristic of the Western Pals- 
arctic region, and, as is clearly indicated by the 
character of their shells, are typically shade- 
loving or woodland species. 
‘his mode of life induces a feeble calcification 
of the shell with a consequent diminution or even 
atrophy of the apertural rib and the development 
of a dull and thick epidermis with a tendency to 
become closely beset with numerous projecting 
hairs or bristles, all peculiarities characteristic of 
a moist and umbrageous environment. 
Occasionally the shells bear a somewhat 
opaque white peripheral zone, an atavic evi- 
dence of some former scheme of ornamentation, 
and that this peculiarity is vestigial is rendered 
probable by the retention of this calcified zone 
and perceptible remnants of the concomitant spiral banding by many 
species belonging to very diverse genera, a circumstance which ‘indubitably 
points to their community of descent from some ancestral banded for m, it 
being quite improbable that such a number of species belonging to so 
many distinct groups should simultaneously evolve nascent banding so 
exactly uniform in character and position. 
A section, under the name Lewcozone, was established by Dr. Westerlund 
to emphasize this character. 
The group was established by Prof. Antoine Risso, of Nice, the celebrated 
Italian naturalist, with whom the genus is here associated. 
30/8/15 
