112 MONOGRAPH OF BRITISH LAND AND FRESHWATER MOLLUSCA. 
GENUS XEROPHILA Held. 
(Helicella, Férussac; Helicopsis, Fitzinger; Jacosta, Gray; Trochula, Schliiter ; 
Turricula, Beck; Cochlicella, Risso, etc.). 
HE genus Verophila (Enpos, dry : pidew, 
to love) i is a subdominant group, which 
in evolutionarily active countries is chiefly 
restricted to arid ground, but if by accident 
or design any of its constituent species are 
transported to primitive and manifestly 
weaker regions, they may monopolize them, 
and oust the competing native species. 
This group is dedicated with the highest 
respect to Dr. Joaquin Gonzalez Hidalgo, 
the distinguished Spanish conchologist, and 
professor of malacology in the University of 
Madrid, in recognition and appreciation of 
his great services to science, and the many 
valuable works he has produced, not only 
upon the fauna of Spain, but upon the 
Philippine Islands and other regions. 
Prof. Pilsbry and others have affirmed 
the alliance of the present group and 
Hygromia, as evidenced by their similarly 
simply -lipped shells, simple form of dart, 
and the frequent duplication of the dart 
sac. ‘his opinion is not corroborated by 
the general character of the shells, which 
in Hygromiu are usually of an uniformly dull brown and bandless, with a 
thickened periostracum, while in .Verophila the shells are characterized 
by their white or whitish calcareous substance and varied dark zonal 
banding—incontestible evidences of a radically different environment and 
mode of life. 
Internally these differences are emphasized in Verophila by the perfect 
freedom of the reproductive organs from the right tentacular retractor, 
which in Hygromia passes between the male and female organs, while the 
stylophores or dart sacs possessed by the typical /ygromiw are paired 
on each side of the vagina, and each pair arranged as a small inner and 
a larger outer sac, the outer one only being teliferous; whereas the 
stylophores of the typical Nerophila itala are of equal size, placed side by 
side, and develop a pair of slender, curved, and intercrossing darts, with a 
common lumen. 
This arrangement in .\. ‘tala suggests that the ancestral form may have 
possessed a pair of teliferous sacs at each side of the vagina, one set of 
which has in VY. itala quite disappeared, while the remaining set is at 
present in process of fusion; further progress in this degeneration i is shown 
in A. virgata, which has now only a single dart, though its stylophore, by 
the occasional presence of an apical cleft, indicates that it was probably 
formerly similar to that of .V. itala; while, according to Moquin-'l'andon, 
the small and more primitive coast form (CY. virgata var. maritima Drap.) 
invariably has the stylophore bluntly bilobed. 
