Shell. Terrestrial, distinguished from the preceding genera by a perfectly round aperture, reflected lip, and horny operculum, summit papillose; left edge having its origin very detached from the spire. Inhabits the East Indies. A few species are found in America. Thirty-eight species.
- Cyclostoma planorbula.
- C. volvulus.
- C. carinata.
- C. sulcata.
- C. unicarinata.
- C. rugosa.
- C. labeo.
- C. interrupta.
- C. ambigua.
- C. semilabris.
- C. tricarinata.
- C. obsoleta.
- C. patulum.
- C. truncatum,
- C. pulchrum.
- C. Jamaicense.
- C. lineolata.
- C. elongatum.
- C. mirabile.
- C. orbella.
- C. aurantium.
- C. flavula.
- C. fasciata.
- C. mumia.
- C. quarternata.
- C. ferruginea.
- C. decussata.
- C. mammillaris.
- C. maculatum.
- C. ligata.
- C. elegans.
- C. tortum.
- C. mirabile.
- · · · · ·
- C. maculata.*
- C. Popayana.*
- C. lapidaria.*
- C. marginata.*
- C. dentata.*
FAMILY VIII.
Lymnacea. Three genera.
1. Genus Lymnea. Pl. [X].
Animal. See Helix.
Shell. Aquatic, oval, sometimes turreted; spire produced, thin, smooth, edges disunited, the left with a very oblique plait rising on the columella, forming an oval aperture, destitute of an operculum. Inhabits the ponds of America and Europe. Thirty-three species.
- Lymnea columnaris.
- L. stagnelis.
- L. palustris.
- L. auricularia.
- L. ovata.
- L. minuta.
- L. luteola.
- L. acuminata.
- L. intermedia.
- L. leucostoma.
- L. peregra.
- · · · · ·
- L. rubiginosus.*
- L. solida.*
- L. Virginiana.*
- L. Emmoniensis.*
- L. lessoni.*
- L. apacina.*
- L. catascopium.*
- L. columella.*
- L. elongatus.*
- L. reflexus.*
- L. appressus.*
- L. elodes.*
- L. limosa.*
- L. lapidaria.*
- L. dissimilis.*
- L. ponderosa.*
- L. integra.*
- L. porata.*
- L. lustrica.*
- L. grana.*
- L. subglobosa.*
2. Genus Physa. Pl. [X].
Animal. See Helix.
Shell. General sinistral, oval, oblong, or globular, very smooth, spire prominent, aperture oval, contracted posteriorly, right edge sharp, columella twisting obliquely, and enlarging to join itself to the anterior part of the margin, the whorls turning to the left hand gives this shell the appellation of heterostrophe. Inhabits the ditches of America and Europe. Ten species.