. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 518 BRIAN MORTON hyaline organs and which were thought to he used for concentrating light upon symbiotic zooxanthellae. Stasek (1966) showed, however, that these structures also possess a sensory function. Examination of the eyes of Laternula truncata in stained section suggests that they are well developed true photoreceptors (Fig. 7). They possess a large lens (LE), lying under a cornea (CO) composed of somewhat flattened cells of the tentacle epithelium. The cup of the eye is composed of three layers which have been named
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 518 BRIAN MORTON hyaline organs and which were thought to he used for concentrating light upon symbiotic zooxanthellae. Stasek (1966) showed, however, that these structures also possess a sensory function. Examination of the eyes of Laternula truncata in stained section suggests that they are well developed true photoreceptors (Fig. 7). They possess a large lens (LE), lying under a cornea (CO) composed of somewhat flattened cells of the tentacle epithelium. The cup of the eye is composed of three layers which have been named by analogy: (1) An outer sclerotic coat (SC) composed of fibrous ma- terial and some muscle fibers. (2) A tapetum (TA) or choroid layer composed of cells containing numerous brown pigment granules (PI). The nuclei of these cells occupy a central or inner peripheral position in the cell. (3) A double retinal layer, in which the proximal layer [Re(l)] is somewhat smaller and darker staining than the distal layer [RE(2)]. The nuclei of these two cell layers are small and PR PA AN. M BG PE SM 1 cm FIGURE 8. Latcrnnla tnincutu, the anatomy and ciliary currents of the organs of the mantle cavity after removal of the left mantle lobe and shell valve. Abbreviations are : AA, Anterior adductor muscle; AN, Anus; AR, Anterior pedal retractor muscle; BG, Byssal groove; CAL, Point of cuticular fusion between the ascending lamella of the outer demi- branch and the visceral mass; CA2, Ctenidial axis; CS, Crack in shell; DD, Digestive di- verticula; E, Exhalant siphon; F, Foot; FG, Ventral marginal groove; I, Inhalant siphon; ID, Inner demibranch; IP, Inner labial palp; M, Mouth; OD, Outer demibranch ; OP, Outer labial palp; PA Posterior adductor muscle; PE, Pedal gape; PR, Pedal retractor muscle; R, Rectum; SG, Sand grains; SM, Siphonal musculature. basally situated. The nuclei are thus arranged in two distinct lines. From the innermost layer are directed towards the lens a large number of t
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
