PULMONATA. 113 



or three folds upon the columella; outer lip sometimes simple and sharp, sometimes 

 thickened, and occasionally denticulated within. 



The genus Auricula, as described by Lamarck, was confined to land shells; and 

 that of Conovulus, proposed by him for certain shells which he considered to be 

 fluviatile, he afterwards suppressed under the impression that they also were land 

 shells. The animals which have been referred to the genus Auricula have, however, 

 various habitats : some are terrestrial ; others live in ponds or fresh-water marshes ; 

 and others, again, are inhabitants of the sea, or are found in brackish water near the 

 mouths of rivers, or in salt-water marshes. Some of these groups are distinguished 

 by peculiarities in the animals or their shells ; and they, accordingly have been with- 

 drawn from Auricula as distinct genera. The present genus, which corresponds with 

 Lamarck's Conovulus, was first separated by Montfort for a shell from the shores 

 of Cayenne. The animal resembles that of Limncea; the head is proboscidiform, 

 notched in front, and furnished with two filiform contractile tentacles, slightly annu- 

 lated, and oculated at their inner bases ; the foot is obovate and obtuse before and 

 behind ; the mantle united to the neck, with the exception of a perforation at the 

 junction of the outer and inner lips. The Melampodes are strictly marine animals, 

 although they are frequently found in brackish waters near the mouths of rivers or salt- 

 water marshes ; they are capable of living out of water for a long period, and Mr. 

 Lowe, in fact, characterises them as amphibious. 



The living species are not numerous ; three are inhabitants of our own shores ; 

 the others are found principally in warm climates. The fossil species hitherto described 

 are from the Eocene and later formations, and have for the most part been referred 

 to Auricula. 



The peculiarity, observed by Montagu in Auricula denticulata, of the columella not 

 extending further than the upper part of the body whorl, is stated by Mr. Gray to be 

 common to most species in the family; and to be caused generally by the animal 

 absorbing the septa which separate the upper whorls, and thus converting the spire 

 into a single cavity, as it enlarges the shell at the edges of the aperture. 



No. 65. Melampus trtdentatus. F. E. Edwards. Tab. X, fig. 4 a — b. 



M. testa ovato-ventricosd, erased, lavi; spird conico-deprcssd, apice obtusiusculo ; 

 anfractibus sex vel septem, sub-cylindraceis, superne depressiuscidis : aperturd auriformi, 

 angustd, labro interne incrassato, antice rejtexo: columella marginatd, tridentatd. 



A thick, smooth, ovate, ventricose shell, with a short conical spire and a bluntish 

 apex ; volutions six or seven, sub-cylindrical, and somewhat depressed round the 

 suture ; the aperture long, narrow, and ear-shaped ; the outer lip rather enlarged and 

 inflected in front, and thickened internally, presenting an elevated sharpish ridge, which 

 extends from a little above the middle of the whorl to the columellar lip. The colu- 



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