. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. Fig. 153. — Eye of Pecten, much en- larged: w,moutn; na) behind I, lens; r, retina and choroid; n, Fig. 154.—Head of a Snail bisected, showing structure of tentacles: a, right inferior ten- tacle retracted within the body; &, right su- perior tentacle fully protruded; c, left supe- rior tentacle partially inverted; left inferi- or tentacle; /, optic nerve ; g, retractor mus- cle; h, optic nerve in loose folds; retractor muscle of head; k, nerve
. Comparative zoology, structural and systematic : for use in schools and colleges. Zoology; Anatomy, Comparative; Physiology, Comparative. Fig. 153. — Eye of Pecten, much en- larged: w,moutn; na) behind I, lens; r, retina and choroid; n, Fig. 154.—Head of a Snail bisected, showing structure of tentacles: a, right inferior ten- tacle retracted within the body; &, right su- perior tentacle fully protruded; c, left supe- rior tentacle partially inverted; left inferi- or tentacle; /, optic nerve ; g, retractor mus- cle; h, optic nerve in loose folds; retractor muscle of head; k, nerve and muscle of left inferior tentacle; I, m, nervous collar. The Scallop (Pecten) has such eyes in the edge of its mantle (Fig. 153). Such organs are the only eyes possessed by Myriapods, Spiders, Scorpions, and Caterpillars. Adult In- sects usually have three ocelli on the top of the head. But the proper visual organs of Lobsters, Crabs, and In- sects are two compound eyes, perched on pedestals, or fixed on the sides of the head. They consist of an immense number of ocelli pressed together so that they take an angular form—four- sided in Crustacea, six-sided in Insects. They form two rounded protuberances variously colored—white, yellow, red, Fig. 155.—Head of the Bee, -1 1 1 i i tt i showingcompoundeyes, green, purple, brown, or black. U nder the three ocelli, or stem- the micrOSCOpe, the Surface is Seen tO ^ta, and the antennas. be divided into a host of facets,95 each being an ocellus complete in itself. Each cornea is convex on one side,. 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 Orton, James, 1830-1877; Birge, E. A. (Edward Asahel), 1851-1950. New York : Harper & Bros.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1883
