. A manual of zoology. Zoology. IV. GASTEROPODA 329 pharynx, which follows, contains the tongue, a ventral ridge supported by one or more cartilages and covered by the lingual ribbon or radula (odon- dophore). The upper surface of the radula is armed with sharp, back- wardly directed teeth (fig. 334) arranged ift transverse and longitudinal rows; these vary so in numljer, form, size, and arrangement that they are of value in classification. The radula is formed in the radula sac, which lies behind the tongue (fig. 334, rs). From this it grows forward like a nail over its bed as fast as it is w
. A manual of zoology. Zoology. IV. GASTEROPODA 329 pharynx, which follows, contains the tongue, a ventral ridge supported by one or more cartilages and covered by the lingual ribbon or radula (odon- dophore). The upper surface of the radula is armed with sharp, back- wardly directed teeth (fig. 334) arranged ift transverse and longitudinal rows; these vary so in numljer, form, size, and arrangement that they are of value in classification. The radula is formed in the radula sac, which lies behind the tongue (fig. 334, rs). From this it grows forward like a nail over its bed as fast as it is worn out in front. It is opposed in eating by a single median or a pair of lateral jaws (lacking in carnivor- ous forms). The rest of the alimentary canal is convoluted, the anus. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
