. Zoology. Zoology. AIR-BREATHING MOLLUSKS. 73 The common snail^, Helix alholalris, is a type of the aii-- breathing mollusks. Fig. 86 represents this snail of natu- ral size, in its shell. The opening to the lung is seen at a, and at B is represented the heart and lung of the garden slug [Limaxfiavus). The eggs of the pond-snails are laid in transparent cap- sules attached to submerged leaves, etc. Those of Physa heterostropha are laid in I the early spring, and three or four weeks | later from fifty to sixty embryos with well-formed shells may be found in the | capsule. The eggs of Limncsus
. Zoology. Zoology. AIR-BREATHING MOLLUSKS. 73 The common snail^, Helix alholalris, is a type of the aii-- breathing mollusks. Fig. 86 represents this snail of natu- ral size, in its shell. The opening to the lung is seen at a, and at B is represented the heart and lung of the garden slug [Limaxfiavus). The eggs of the pond-snails are laid in transparent cap- sules attached to submerged leaves, etc. Those of Physa heterostropha are laid in I the early spring, and three or four weeks | later from fifty to sixty embryos with well-formed shells may be found in the | capsule. The eggs of Limncsus are laid late ir the spring in capsules containing one oi two eggs, and surrounded by a mass o] jelly. Land£ggpls and slugs lay their eggs loose opmei" damp leaves and stones, and fiq. 85.—siug; natural develOpiuent is direct, the young snail ^'''''• hatching in the form of the adult. Various shells, such as Marginella, Turbinella, etc., are. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Packard, A. S. (Alpheus Spring), 1839-1905. N. Y. , Holt
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1897
