. Elements of zoölogy : a textbook. Zoology. oil LAMHLLIBHANCHIATA. The mouth is situated at the anterior side or end ; it has no teeth, but has two pairs of labial tentacles. The stomach, intestine, and liver ara well devel- oped. The heart has one auricle—in some cases di- vided into two—and one ventricle, and the intestine passes through it. The gills or branchiae consist of two pairs of delicate and finely-striated t membran- ous plates situated just be- neath the mantle. The gills not only serve for the processes of respiration, but by means of their vi- bratile cilia they waft
. Elements of zoölogy : a textbook. Zoology. oil LAMHLLIBHANCHIATA. The mouth is situated at the anterior side or end ; it has no teeth, but has two pairs of labial tentacles. The stomach, intestine, and liver ara well devel- oped. The heart has one auricle—in some cases di- vided into two—and one ventricle, and the intestine passes through it. The gills or branchiae consist of two pairs of delicate and finely-striated t membran- ous plates situated just be- neath the mantle. The gills not only serve for the processes of respiration, but by means of their vi- bratile cilia they waft cur- rents of water bearing food to the mouth, and they form a place for the hatch- ing of the eggs. Most of the Acephals effect locomotion by means of the muscular " foot," which in many species is very large and powerful; and in the boring species, as PJiolas, Teredo, etc. (Figs. 632-4), it is studded with siliceous particles. Some kinds, as fresh-water Flo. ill. Clam, Myn arennria. left valve, mantle lobe, arid half tbo siphons removed. h, heart; m. cut-edge of the man- tle ; o, .nonth : s. siphon into which the water flows to bathe the gills allfl to carry particles of food ; «', siphon which carries the outflowing current; t, labial tentacles; v, vent. a. a', adductor muscles; ft, body; c, cloaca ; /, " foot" ; y, gills or bran- 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 Tenney, Sanborn, 1827-1877. New York : Scribner
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