INVOLUTE. ] 
6. Urricutus canpipus, pl. XIX, f. 13, 14.—First Ed., 
pl. 38, f. 13, 14. 
Diaphana candida, Brown, Conch. Text Book, p. 98, pl. 14, 
f. 30. 
Shell oblong, oviform, snow-white, diaphanous, and pellucid ; 
body very large, and much inflated; spire very small, sunk in a 
hollow foss, consisting of two yolutions, the apicial one blunted, 
papilleform, having much the appearance and lustre of a minute 
pearl; aperture as long as the body, nearly pyriform, contracted 
above, but widening gradually to an expanded and rounded 
base; outer lip thin, and even on the edge; pillar lip slightly 
reflected on the columella, with a slight internal wave on its 
centre, and a subumbilicus behind; body faintly wrinkled lon- 
gitudinally towards the outer lip. Length one-twelfth of an 
inch; diameter nearly the same. 
Found at Dunbar, by General Bingham; and I have since 
met with it at Holy Island, coast of Northumberland. 
7. Urrrcutus peLLucipus, pl. XIX, f. 10, 11.—First Ed., 
pl. 38, f. 10, 11. 
Shell oblong-ovate, very thin, diaphanous and pellucid, and 
of a bluish or snow-white ; body very large; spire consisting of 
one rounded volution, resembling a small pearl, surrounded by 
a fossus, formed by the upper part of the body, which is ob- 
liquely elevated considerably above it; aperture a little longer 
than the body, contracted above, widening below, and termi- 
nating in a well rounded base; outer lip thin, and even on the 
edge; pillar lip thickened, and slightly reflected on the colu- 
mella, but destitute of any umbilical mark. Length a twelfth 
of an inch; diameter about a fourteenth. 
~ Found at Dunbar, by General Bingham. 
This species differs from the U. candidus, in being more ob- 
long, the body less inflated and more cylindrical, the outer lip 
less expanded at the lower portion of the aperture, and the spire 
in having one volution; the outer lip also turns a little upwards, 
and curves a little inwards above before it expands, whereas the 
lip of the U. candidus gradually developes from its insertion. 
8. UrricuLUs HYALINA. 
Bulla hyalina, Turton, Mag. Nat. Hist., VII, p. 353; Bulla 
Roxwama, Leach. 
“Shell oval, transparent, smooth; aperture dilated at the base; 
pillar umbilicate ; crown flattened, channelled, umbonate. 
“Tt something resembles the Bulla wmbilicata; but is short- 
er, and of a more oval shape, with the aperture more dilated, 
and is of a crystalline transparency. At the base of the margin 
there is a reflection of the pillar, forming a slight groove or 
umbilicus; and the central umbo on the crown is very distinct 
and prominent. ‘The last two marks seem to fix it in the genus 
Cymba of Lamarck and Sowerby. but we have not remarked 
the sharp plaits on the pillar. 
“Found abundantly on the coast about Tynemouth; whence 
it was sent us by Mr. Alder. We also discovered it near the 
Land’s End, Cornwall.”— Turton. 
Genus 7.—AKERA.—Brown. 
Shell extremely thin, horny, and elastic; apex obtuse; suture 
of the spire canaliculated, and the volutions for the most part 
not protruding beyond the body; aperture extending the whole 
length of the body, always contracted above, and expanded 
below; the outer lip separated from the body yolution. 
MOLLUSCA. 59 
1. AKERA FLEXILIS, pl. XIX, f. 31, 32.—First Ed., pl. 38, 
Feitliscae 
Akera flevilis, Brown, Conch. Text Book, p. 98, pl. 14, f. 
29; Ib., Popular Ency., II, p. 378, pl. 17, £.109; Bulla Akera, 
Miiller, Zool. Dun., p. 71, f. 2 and 5; Montagu, p. 219; Maton 
and Rackett, p. 125; Brown, Wernerian Mem., II, p. 516; 
Ib., Ency. Brit., VI, p. 4345; Fleming, p. 292; Bulla resilins, 
Donoyan, pl. 79; Bulla fragilis, Lamarck, VI, pt. 2nd, p. 36. 
Shell oblong-ovoid, extremely thin, pellucid, horn-coloured, 
and elastic, somewhat wrinkled longitudinally; spire small, 
canaliculated, with an obtuse apex, and not protruding beyond 
the body; aperture white, as long as the body, acutely con- 
tracted above, very wide, and rounded below; outer lip ex- 
tremely thin and elastic, the upper portion lying close to the 
body volution, but detached, and adherent to the lower volu- 
tions of the spire; pillar lip white, a little thickened, and reflect- 
ed over the columella, which is visible to the end. Length one 
inch; diameter somewhat more than half its length. 
This species is so extremely thin and membranaceous, that it 
appears an extremely delicate shell, which, however, is not the 
case. Some of them are transparent horn-coloured, both inter- 
nally and externally. 
Found in many places on the coasts of Britain and Ireland ; 
and we may particularise Banff, in Scotland; Lymington, Poole, 
Dorsetshire, and near Southampton; and I met with it in vast 
numbers, amongst sea weed near high water mark, at Warren 
Point, near Dundalk, Ireland. 
Famity IJ].—AnNcyYLip2. 
Animals fluviatile ; they breathe air, respiring on the surface 
of the water; breathing apparatus situate in a bag-shaped cavity 
on the back of the neck. 
Genus 8.—AncyLus—Miiller. 
Shell thin, obliquely conical, patellieform; vertex somewhat 
pointed, short, turned backwards, and inwards, but not spiral : 
aperture oval, or oblong, with the margins simple and entire. 
Section I—Animals sinistral. 
1. ANcyLus FLuvr1aTILis, pl. XII, f. 1, 4, and 6.—First 
Ed., pl. 36, f. 1, 4, and 6. 
Ancylus fluviatilis, Miller, Verm., II, p. 194, No. 381; Dra- 
pernaud, p. 48, pl. 2, f. 23, 24; Pfeiffer, p. 107, pl. 4, f. 44, 45; 
Brard, p. 200, pl. 7, f.3; Turton, Man., p. 140, pl. 10, f. 125; 
Alder, Mag. Zool. and Bot., II, p. 116; Thompson, Ann. and 
Mag. Nat. Hist., VI, p. 47; Lamarck, VI, pt. 2nd, p. 27; 
Patella fluviatilis, Montagu, p. 484; Liuné, p. 1253; Da Costa, 
p- 48, pl. 3, f. 8; Patella lacustris, Donovan, pl. 147, f. 2; 
Maton and Rackett, p. 232; Brown, Ency. Brit., VI, p. 466; 
Ib., Wernerian Mem., II, p.533; Crepedula lacustris, Fleming, 
Edin. Ency. 
Shell subconic, with the vertex sharp, slightly recurved, and 
situate near one end, sometimes a little hooked; pellucid, horn- 
coloured, covered with a dark greenish-brown epidermis, some- 
times of a paler hue, beneath which the shell is of a brown 
horn-colour, and with a few concentric wrinkles; aperture oval; 
marginal lip thin; inside glossy, of a bluish-white. Length 
three-eighths of an inch; breadth a quarter of an inch. 
