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HYALINIA RADIATULA PETRONELLA. 
H. radiatula petronella Charp. 
Flelix petronella Charp., in Pfeiffer, Mon. Helic. Viv., 1853, iii., p. 95. 
Zonites dumontianus Bourguignat, Mal. Aix les Bains, 1864, p. 26. 
Helix petronedla var. cenisia Pollonera, Moll. Verr. viv. Piemonte, 1885, p. 11. 
Original Description.—‘‘402. H[elix] petronella Charpentier. 'T. umbilicata, 
depressa, tenuis, superne distinete et confertim plicatula, pellucida, virente- 
hyalina ; spira convexiuseula ; sutura impressa, submarginata ; anfr. 4 planiuseuli, 
ultimus depresse rotundatus, non descendens, basi convexiusculus ; umbilicus 
angustus pervius ; apertura parum obliqua, lunato-rotundata ; peristome simplex, 
tenue, rectum, margine columellari superne vix dilatato. Diam., maj. 5, min. 44, 
alt. 24 mill. (Mus. Cuming). 
Helix petronella Charpent., MSs. 
Habitat in summis Alpibus Helvetize rarissime.”—L. PFEIFFER, Mon. Helie. 
Vivent., 1853, iii., p. 95. 
The var. ecenisia Pollonera = Hyalina dumontiana Lessona, not Bourguignat, 
is hyaline, vitreous, narrowly umbilicated, mouth rounder and less oblique. 
The Z. dumontianus is probably a small form of radiatulus, distinguished by 
its more distant costulations, narrower and less trumpet-shaped umbilicus, its less- 
dilated, perfectly rounded last whorl, and its aperture round and not oblong. 
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Fic. 135.—Zonites dumontianus Bourguignat, enlarged and natural sizes (after Bourguignat). 
H. radiatula petronella was discovered by Venetz in 1820, and specimens were 
sent by Charpentier under the name of Helix vitrina to Férussac, who conserved 
the name in his great work. It differs from the typical form by its larger size, 
loftier spire, wider umbilicus, stronger spiral striation, 1ts usually uniform greenish- 
white colour and almost hyaline transparency, but more especially by the aperture 
and Jast whorl being rounded instead of compressed and oval. 
The radula of H. petronella extracted from a specimen sent from Dalarne in 
Sweden by Dr. Westerlund, is described by Heer Schepmann as showing a formula 
of 26+84+14+8+2 and as differing only slightly from those of Dutch specimens of 
H. hammonis, by the possession of six more longitudinal rows of teeth, which, 
though of slightly larger size, offered no characters for special diagnosis. 
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Fic. 136.—Representative denticles from a transverse row of the teeth of //yalinia fetronella Charp., 
from Dalarne, Sweden, per Dr. C. A. Westerlund, x 600 (after Schepmann). 
This form has been well studied, and some of its slighter local modifications 
have been noticed and named by various authors. Amongst others M. Bourguignat 
has described from Aix les Bains a Zonites dumontianus ; another variety from 
Barcelona, which he has named jucetanica, Dr. Bottger affirms is but the usual 
horn-coloured form, and also states that H. swbnitidosa Mousson is identical with it. 
According to Westerlund, this form is plentiful throughout Finland and the 
whole of Scandinavia, extending also over the Kola peninsula in the government 
of Archangel in Arctie Russia. It is also found in Iceland, Ireland, South Wales, 
and throughout Middle and Southern Europe, almost always at considerable heights 
on the mountains, a8 in Saxon Switzerland; on the Styrian and Tyrolese Alps ; 
on the mountains of South Germany. In the Valais and Savoyan Alps, where it 
exists at about 6,000 feet altitude, as well as in Piedmont, Switzerland, Auvergne, 
the Pyrenees, and the northern provinces of France, 
