Involute.] 



MOLLUSCA. 



59 



6. Utriculus candidus, pi. XIX, f. 13, 14 First Ed., 



pi. 38, f. 13, 14. 



Diaphana cayidida, Brown, Concli. Text Book, p. 98, pi. 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 volutions, the apicial one blunted, 

 papilkcform, 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. Utriculus pellucidus, pi. XIX, f. 10, 11 First Ed., 



pi. 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. Utriculus hyalina. 



Bulla hyalina, Turton, Mag. Nat. Hist., VII, p. 353; Bulla 

 Roxama, Leach. 



" Shell oval, transparent, smooth; aperture dilated at the base; 

 pillar umbilicate ; crown flattened, channelled, umbonate. 



"It something resembles the Bulla urnbilicata; 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 ~. — 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 volution. 



1. Akera flexilis, pi. XIX, f. 31, 32 — First Ed., pi. 38, 

 f. 31,32. 



Akera flexilis, Brown, Conch. Text Book, p. 98, pi. 14, f. 

 29; lb., Popular Ency., II, p. 378, pi. 17, f. 109; Bulla Akera, 

 Muller, Zool. Dun., p. 71, f. 2 and 5; Montagu, p. 219; Maton 

 and Rackett, p. 125 ; Brown, Wernerian Mem., II, p. 516 ; 

 lb., Ency. Brit., VI, p. 434; Fleming, p. 292; Bulla resilins, 

 Donovan, pi. 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. 



Family III. — Ancylid^e. 



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 Muller. 



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 fluviatilis, pi. XII, f. 1, 4, and 6. — First 

 Ed., pi. 36, f. 1, 4, and 6. 



Ancylus fluviatilis, Muller, Verm., II, p. 194, No. 381 ; Dra- 

 pemaud, p. 48, pi. 2, f. 23, 24; Pfeiffer, p. 107, pi. 4, f. 44, 45; 

 Brard, p. 200, pi. 7, f. 3 ; Turton, Man., p. 140, pi. 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; Linne, p. 1253; Da Costa, 

 p. 48, pi. 3, f. 8 ; Patella lacustris, Donovan, pi. 147, f. 2; 

 Maton and Rackett, p. 232 ; Brown, Ency. Brit., VI, p. 466 ; 

 lb., 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. 



