. Elementary text-book of zoology [electronic resource]. Zoology. ANODONTA. 271 run across from shell to shell, and their contraction draws the shells together. Inside each adductor scar is a smaller round scar, caused by the anterior and posterior retractors, which serve to draw the foot into the shell. Lastly, near the anterior adductor scar is a small protractor scar, the muscle serving to draw the foot forward. 'I he attachments of the muscles shift outwards and downwards as the shells grow. Fig. 188.—Internal View of Right Shell of Anodon. {Ad. ?iat.) Am. When the shells are [forced open
. Elementary text-book of zoology [electronic resource]. Zoology. ANODONTA. 271 run across from shell to shell, and their contraction draws the shells together. Inside each adductor scar is a smaller round scar, caused by the anterior and posterior retractors, which serve to draw the foot into the shell. Lastly, near the anterior adductor scar is a small protractor scar, the muscle serving to draw the foot forward. 'I he attachments of the muscles shift outwards and downwards as the shells grow. Fig. 188.—Internal View of Right Shell of Anodon. {Ad. ?iat.) Am. When the shells are [forced open they expose a large mantle cavity. This is bounded dorsally by the body of the animal, and laterally by the lateral mantle-folds ; ventrally it is widely open to the exterior, except when the shells are shut. The mantle-flaps line the inner surface of the shells, which they secrete. The free edges are pressed together, except at the posterior end, where they diverge to form a large ifihalent opening, then meet, and again diverge to form the smaller exhalent opening. In the centre of the mantle-cavity a large muscular foot depends downwards, and on occasion it can be protruded outwards between the shells. Embedded in the foot, near the pedal ganglia, are the otocysts, but Anodonta has no eyes. There is a pair of osphradia or sense-organs of an olfactory nature at the base of the gills innervated from the visceral 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 Masterman, Arthur Thomas; Parsons, John Herbert, Sir, 1868-1957, donor; S. H. Lazarus (Firm); University College, London. Library Services. Edinburgh : E. & S. Livingstone
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1901
