. Elementary text-book of zoology. 272 MOLLUSC A. On either side of the foot there hang the gill-lamella, or ctenidia. These are lamellae on each side, formed in each J, . case by a gill-plate folded on itself, the outer gill-plate outwards and the inner inwards. The gill-plates are themselves composed of a number of gill- Jilaments, which hang perpendicularly in a single row from a horizontal axis which is fused with the body-wall. Fig. 191—View of Anodonta with Left Mantle-Flap thrown Bacic. (Ad nat.) Left Mantle Inhalent Aperture. Outer Gill. Renal Inner Gill. Foot. Labial Genital Ap
. Elementary text-book of zoology. 272 MOLLUSC A. On either side of the foot there hang the gill-lamella, or ctenidia. These are lamellae on each side, formed in each J, . case by a gill-plate folded on itself, the outer gill-plate outwards and the inner inwards. The gill-plates are themselves composed of a number of gill- Jilaments, which hang perpendicularly in a single row from a horizontal axis which is fused with the body-wall. Fig. 191—View of Anodonta with Left Mantle-Flap thrown Bacic. (Ad nat.) Left Mantle Inhalent Aperture. Outer Gill. Renal Inner Gill. Foot. Labial Genital Aperture. Palp. Aperture, A ctenidium therefore consists of a medium axis with two rows of gill-filaments, each row forming a gill-plate. In Anodonta. but not in all Lamellibranchiata, these gill-plates are bent double to form in each case two gill-lamellae. In addition, the filaments and the gill-lamellae have fused with their fellows and thus form a network of filaments. The whole are ciliated and cause currents of water and food- particles to pass into the mantle-cavity by the inhalent aperture. The free edges of the upturned gill-plates are fused to the body-wall, and thus shut off outer and inner. 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. Edinburgh, E. & S. Livingstone
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