• WordNet 3.6
    • n Gasteropoda snails and slugs and their relatives
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Webster's Revised Unabridged Dictionary
    • n. pl Gasteropoda (Zoöl) Same as Gastropoda.
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Century Dictionary and Cyclopedia
    • gasteropoda A group of mollusks to which different values and limits have been assigned. Originally it was considered by some as a section and by others as an order of the mollusks, which were then ranked as a class. Later it was raised to a class and almost universally accepted as such. It has generally been customary to include in it all the mollusks with a distinct head and foot developed from the abdominal surface, thus contrasted with the classes Cephalopoda and Pteropoda. By many it has been extended to include all having a head, thus embracing the Pteropoda and excluding only the Cephalopoda. By others it has been restricted to those having a distinct head, abdominal foot, and a spiral, subspiral, or low oval or conic shell or naked body, thus excluding the Scaphopoda. By others still it has been further cofined to those having a spiral or subspiral shell or naked body, and a more or less asymmetrical arrangement of the internal organs, the Chitonidæ and some naked related types being consequently eliminated. Within even the narrowest limits assigned to it, the class is very diversified. Generally a univalve shell is developed, but in many forms of several orders or suborders the shell is obsolete or entirely absent in the adult. Even in the naked forms, however, the embryo or larva is generally provided with a shell. The shell is usually spiral, or rather of an elongated conic form wound round in a spiral coil, but varying from a very high turreted form to a discoid or even sunken spire, an intermediate stage being the most common; in various types it is of a broad conic or patelliform shape, and in others, especially the terrestrial slugs, it is reduced to a scale-like element concealed under the mantle. The shape of the shell generally agrees with the structure of the soft parts, but sometimes differs so much that a gastropod can only be properly classified by examination of the anatomy of the animal. In most marine species, as well as in many terrestrial ones, an operculum more or less closing the aperture of the shell is developed from the foot of the animal; but in most of the land-shells (Pulmonifera) it is wanting. One of the distinguishing characteristics of Gasteropoda, giving name to the class, is the foot, which is generally broad, muscular, and disk-like, and attached to the ventral surface; but in some it is obsolete, and in others, as the heteropods, compressed and adapted for swimming. The garden-snail may be regarded as a typical gastropod. The class comprises also whelks, periwinkles, limpets, cowries, and many other univalve or shell-less forms. No known gastropod has a bivalve shell. Cochlides is a synonym.
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In literature:

Of the many living Gasteropoda taken in this region, very few are new species.
"Voyage Of H.M.S. Rattlesnake, Vol. 2 (of 2)" by John MacGillivray
"The Ancient Life History of the Earth" by Henry Alleyne Nicholson
In the next higher class of the Gasteropoda, or marine univalve shells, the sexes are either united or separate.
"The Descent of Man and Selection in Relation to Sex, Vol. I (1st edition)" by Charles Darwin
SHELLS, difference in form of, in male and female Gasteropoda, i.
"The Descent of Man and Selection in Relation to Sex" by Charles Darwin
The Brachiopoda are still interposed between the Conchifera and Gasteropoda.
"British Quarterly Review, American Edition, Volume LIV" by Various
Gasteropoda, classification of, 29.
"Stories of the Universe: Animal Life" by B. Lindsay
I may notice here two other land shells, although they scientifically are grouped amongst the fluviatile Gasteropoda.
"Our British Snails" by John William Horsley