( 31 ) 



a Helix, Lam. Globulous, pi. 7, fig. 9- 



b Caracolla, Lam. Carinated, conical, pi. /, "g- 



c Anostoma, Lam. Mouth dorsal, toothed, pi. /, 



18. Helicina. (1) Lam. 



Subglobulous or coni- 

 cal ; spire a little depress- 

 ed ; inner lip enlarged at 

 the base in a callous pad 

 entirely covering the um- 

 bilicus ; a small blunt an- 

 gle at the base of the right 

 lip. PI. 12, fig 6. 



20. Ampullaria. (2) Lam. 



Round and ventricose, 

 spire short.; umbilicate ; 

 operculum horny. 



a. 



Mouth narrower, 

 more elliptical,thinner. 

 PI. 9, fig. 1. 



Columella callous. 



Inner lip sharp. 



Terrestrial. 



V. Animal, p. 66. 



Marine. 



Australasia. 



V. Animal, p. 62. 



Fresh Waters of warm 

 climates. 



19. Helicarion. Ferruss. 

 Very thin, transparent. 



Columella spiral, solid, 

 formed by the inner lip 

 and confounded with the 

 whorl of the mouth. 



Columella umbilical. 



b. AmpuUina. 



Considerably thick- Marine. 

 er. PI. 9, fig. 2. V. Animal, p. . 



method of distribution, impressing that it is purely artificial. The Helices being 

 terrestrial shells, it appears extraordinary that we should meet with them in the 

 fossil state in marine deposits; but when that happens they have been brought 

 there by floods or rivers, or by some irruption of the sea, attesting that previously 

 to these deposits there had been dry land in the same places, whereon the animals 

 lived which formed the shells. The Marl Pit of Touraine is the only place on 

 record where they thus occur, and there they are frequeutly filled with the remains 

 of Polypi and marine shells. Fossil Helices are generally found in Fresh Water 

 Formations, and often accompanied by Lymnsei and Planorbes. We meet with 

 them in breccia, and sometimes in the districts which have been overthrown by 

 volcanoes. In England they have been found in the Covues Rock of Limestone, in 

 the Green Sand, and in the Derbyshire Peak Limestone. 



(1) Foss. B lue Lias Limestone. 



(2) Their opercula, being horny, are never found, although these shells are very 

 common in beds of coarse, calcareous, shelly matter ; whilst the opercula of the 

 Naiicaz, to which some authors would refer them, are very frequently met with, 

 from their being calcareous. Fossil Ampullariae are also found in the extinct vol- 

 canoes of the valley of Ronca, where they have been so disposed by the eruptions 

 as to preserve their colours. M Faujas found a species of Ampullaria, with a very 

 thick shell ,at St. Paulet, near Pont St. Esprit, in bituminous marl, above a mine of 

 fossil coal; the upper edge of each whorl bears an ascending keel, and it differs 

 from all that are inown, by an oval mouth, pi. 12, fig 12. 13, 14. 



