. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. THK ()!•' LATERNULA TRUNCATA 519 The musculature. The anterior and posterior adductor muscles are small (Figs. 1 and 9, AA, PA), the latter somewhat the larger. A similar condition exists in Clavagella (Soliman, 1967) and in Cnspidaria and Poromya (Yonge, 1928). In Brechites, the posterior adductor is absent and the anterior adductor is very much reduced (Purchon, 1956). Internally to these two muscles are inserted the anterior (AR) and the posterior (PR) pedal retractors. The latter are very small. These muscles ser
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. THK ()!•' LATERNULA TRUNCATA 519 The musculature. The anterior and posterior adductor muscles are small (Figs. 1 and 9, AA, PA), the latter somewhat the larger. A similar condition exists in Clavagella (Soliman, 1967) and in Cnspidaria and Poromya (Yonge, 1928). In Brechites, the posterior adductor is absent and the anterior adductor is very much reduced (Purchon, 1956). Internally to these two muscles are inserted the anterior (AR) and the posterior (PR) pedal retractors. The latter are very small. These muscles serve to move the foot (F), which in the adult is very small and ineffectual as a digging tool. In Clavagella, the foot is very reduced and the pedal retractor muscles absent (Soliman, 1967). The foot of Latcrnnla truncata possesses strong ciliary currents and the tip of the foot was often observed between the lips of the mouth, where it may act as an accessory organ for the removal of sediment. A similar habit has been observed in Dreissena polymorpha (B. S. Morton, 1969) and Adula jalcata (Fankboner, 1971). The foot of L. tntncata possesses a small byssal groove (Figs. 8 and 9, BG) but there is no functional byssal gland in the adult as there is in Lyonsia norvegica AR AA AN. PE SS TE SG ID CM SM 1 cm FIGURE 9. Latcrnnla truncata, the general anatomy and the ciliary currents of the mantle cavity after removal of the left shell valve, mantle lobe, labial palps and ctenidium. Abbrevia- tions are: AU, Auricle; CA3, Point of cuticular fusion between the ascending lamella of the inner demibranch and the visceral mass; CM, Cut edge of mantle; FA, Free ctenidial axis; K, Kidney; MG, Mid gut; O, Ovary; OV, Oviduct; P, Pericardium; RP, Reno-pericardial aperture; SB, Supra-branchial chambers; SS, Style sac; TE, Testis, U, Urino-genital aperture; V, Ventricle; VD, Vas deferens. (Other abbreviations as in Figure 8.) (Ansell, 1967) and Mytilimeria and Entodesma (Yonge, 1952). Cnspidaria an
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
