. Zoology : for students and general readers . Zoology. Fio. 196. Fig. 197. velum ; ,«, shell ; d, foot; b^ otocysts.—After Fig. 198.—Physa ^^terosiropha. Com- mon pond-snail.—After Morse. Fig. 195.—. Fig. 196. — Veliger of Tergipes Schultze. Fig. 197.—Doris. New England coast. shelless, and not uncommon just below low-water mark, laying their eggs in jelly-like masses coiled up on stones and the surface of sea-weeds. Though the adults are shelless, the embryos at first have a shell (Fig. 196, s), indicating that the Nudibranchs have descend- ed from shelled G-astro
. Zoology : for students and general readers . Zoology. Fio. 196. Fig. 197. velum ; ,«, shell ; d, foot; b^ otocysts.—After Fig. 198.—Physa ^^terosiropha. Com- mon pond-snail.—After Morse. Fig. 195.—. Fig. 196. — Veliger of Tergipes Schultze. Fig. 197.—Doris. New England coast. shelless, and not uncommon just below low-water mark, laying their eggs in jelly-like masses coiled up on stones and the surface of sea-weeds. Though the adults are shelless, the embryos at first have a shell (Fig. 196, s), indicating that the Nudibranchs have descend- ed from shelled G-astropods. Fig. 196 represents the veli- ger of Tergipes lacinulata Schultze, allied to Doris, with its large ciliated velum, and protected by a deciduous shell, which finally disappears with the velum. The air-breathing mollusks, Pulmonata, are represented by the pond-snails, Physa (Fig. 198) and Limnwns (Figs. 199, 200), and the land-snails and slugs. Fig. 205 represents a slug suspended by a mucous thread from a twig. The common snail. Helix alholahris Say, is a tjrpe of the air-breathing mollusks. Fig. 301 represents this snail of natural size, in its shell. The opening to the lung is seen at a, and at B is represented the heart and lung of the gaiN den slug (Limax flavus). Fig. 202 rejjresents Helix alio- Inbris with the shell removed, and the mantle thrown back,. 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. New York : Henry Holt
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1879
