. The Cambridge natural history. Zoology; Zoologia Geral. vr BREATHING ORGANS IN PROSOBRANCHIATA 157 which included Patella and Chiton^ has no value, and has indeed long been discarded. In Chiton the gills never extend completely round the animal, but are always more or less interrupted at the head and anus. They are the true gills, the plumes being serially repeated in the same way as the shell Fig. 63. — Patella vuU/ata L., seen from the ventral side:/, foot; , circlet of gill lamellae; , edge of tlie mantle; mu, attachment muscle; ^7, slits in the same ; sh, shell; v, vessel
. The Cambridge natural history. Zoology; Zoologia Geral. vr BREATHING ORGANS IN PROSOBRANCHIATA 157 which included Patella and Chiton^ has no value, and has indeed long been discarded. In Chiton the gills never extend completely round the animal, but are always more or less interrupted at the head and anus. They are the true gills, the plumes being serially repeated in the same way as the shell Fig. 63. — Patella vuU/ata L., seen from the ventral side:/, foot; , circlet of gill lamellae; , edge of tlie mantle; mu, attachment muscle; ^7, slits in the same ; sh, shell; v, vessel carrying aerated blood to the heart; u', vessel carrying blood from the heart; ve, small accessory vessels. Fig. 64. — Patella vulgata L., seen from the dorsal side after the removal of the shell and the black pigment covering the integument; the anterior portion of the mantle is cut away or turned back: (/, anus; hr, br, remains of the true branchiae (ctenidia); /, intestine; k,k', kidneys; , their apertures on each side of the anus; /, liver; ni, m, mantle; mu, attachment muscles, severed in re- moval of shell; t, t, tentacles. In the land Prosobranchiata (Cyclostomatidae, Cyclophoridae, Aciculidae, Helicinidae) which, having exchanged a marine for an aerial life, breathe air instead of water, the branchia has completely disappeared, and breathing is conducted, as in the Pulmonata, by a lung-cavity. In certain genera of land oper- culates, Pupina^ Cataidus^ Pterocf/clus^ a slight fissure or tube in the last whorl (see Fig. 180, p. 266) serves to introduce air into the shell, which is perhaps otherwise closed to air by the oper- culum. In Aulopoma^ which has no tube, the operculum admits free circulation of air. In certain other Cyclostomatidae the apex is truncated, and air can enter there. De Folin closed with wax the aperture of Oi/cl. elegans, and found that on plac- ing it in a pneumatic machine, the shell gave off air through its. Please note that these imag
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
