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The Mating of the Landsnail Haplotrema concavum (Say)

Glenn R. Webb
The American Midland Naturalist
Vol. 30, No. 2 (Sep., 1943), pp. 341-345
Published by: University of Notre Dame
DOI: 10.2307/2421286
Stable URL: http://www.jstor.org/stable/2421286
Page Count: 5
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The Mating of the Landsnail Haplotrema concavum (Say)
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Abstract

1. Mollusca, Gastropoda, Pulmonata, Haplotrematidae. The present contribution is a study of the mating of captive specimens of Haplotrema (Geomene) concavum (Say) with reference to the anatomy, behavior, and functioning of the sex organs. 2. In mating one animal mounts the other's shell. When over the aperture, the upper animal reaches downward and the lower upward. They begin gnawing at each other's foreparts, which become entwined. Copulation commences, following the eversion of penis and atrium, with the insertion of the penis into the vagina. About this time neck gnawing ceases. F. C. Baker's ten-hour coitus duration record for the species remains unsupplemented. Mating season data are given and the possibility of self-fertilization is considered. 3. The club-shaped, papillose penis is divided into a basal stalk and an ovoid apical part. The everted atrium appears as a fleshy, lobate disk continuous with the penis and vaginal orifice. The vagina extends from the orifice to the lower flexure and the free oviduct from there to the uterus. 4. The penis penetrates the vagina to the sigmoid flexure. The orifice of the spermathecal duct is below the tip of the inserted penis. It is suggested that the atrial disk has the function of a protective neck shield.

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