LIMNiflUS. 169 



body and aperture are often less ample than in dextral 

 specimens. 



In the lutea of Montagu the shell is stronger and dull 

 orange yellow ; the mouth large ; the spire depressed. Tn 

 the shell figured in the Linnean Trausactions (vol. viii. pi. 

 5, f 8*), and in the marginata of Michaud, the internal 

 rim of the outer lip is thickened. 



The usual size of this species is about half an inch in 

 length, but there are varieties an inch long, and others con- 

 stantly dwarfed. 



The animal has a very broad head with large triangular 

 tentacles, the eyes placed on slight auriculations at their 

 inner bases. The foot is broad and round in front, obtuse 

 but somewhat lanceolate behind. The general colour is a 

 yellowish olive, varying in depth, changing to greenish grey 

 at the margin, and deepening to brown or mottled black on 

 the body. This is our commonest Limnfeus, and is univer- 

 sally diffused through the British islands : it is found in 

 springs high u}) on mountains, as well as in ponds by the 

 sea-shore nearly brackish. 



L. AURICULAEIUS, Liuuffius. 



Almost as broad as long, inflated, wrinkled ; spire acute, very 

 short, its whorls not rounded ; penult turn very narrow, abruptly 

 larger than the previous coil, truncated conical. Mouth very 

 capacious ; columellar fold prominent ; outer lip patulous, pro- 

 jecting above almost at right angles to the axis. 



Plate CXXIII. fig. 1 and (var.acutus) 2. 



ScHROTER, Fl'iissconch. p], 6, f. 4, 5 ; pi. 7, f. 12. 

 Heliw aiiricularia, Linn. Sj'st. Nat. ed. 12, p. 1249. — Penn. Brit. Zool. ed. 4, 

 vol. iv. p. 139, pi. 86, f. l.'iS.— PuLTENEV, Hutchins, Hist. 

 Dorset, p. 49.— Donov. Brit. Shells, vol. ii. pi. 51, f. 1. — 

 Mont. Test. Brit. p. 375, pi. 1 «, f. 2.— Maton and Rack. 

 Trans. Linn. Soc. vol. viii. p. 221 (not var.). — Dorset 



VOL. IV. Z 



