. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. Fig. 170. — Eye OP Lacerta niu- ralis, SHOWING THE Ring of Bony Sclero- tic Fig. 171.—Eye of an Owl. Rt, retina ; Ch, Choroid; Sc, sclerotic, with its bony ring at t : CM, ciliary muscle; Co, cornea; VN, point of jvmction between sclerotic and cornea ; Jr, iris; VK, anterior chamber; L, lens ; Cr, vitreous humour ; P, pecten; Op, OS, optic nerve and sheath. The dotted line passing across the broadest portion of the circumference of the eye divides the latter into an inner and an outer segment. outer portion is
. Elements of the comparative anatomy of vertebrates. Anatomy, Comparative. Fig. 170. — Eye OP Lacerta niu- ralis, SHOWING THE Ring of Bony Sclero- tic Fig. 171.—Eye of an Owl. Rt, retina ; Ch, Choroid; Sc, sclerotic, with its bony ring at t : CM, ciliary muscle; Co, cornea; VN, point of jvmction between sclerotic and cornea ; Jr, iris; VK, anterior chamber; L, lens ; Cr, vitreous humour ; P, pecten; Op, OS, optic nerve and sheath. The dotted line passing across the broadest portion of the circumference of the eye divides the latter into an inner and an outer segment. outer portion is bounded ex- ternally by the very convex cornea and encloses a large anterior chamber as well as a complicated ciliary muscle com- posed of striated fibres. This muscle is also transversely stri- ated in Reptiles, in which— especially in Chelonians, it is always well developed, though . not to such an extreme degree as in Birds. In Reptiles (Lizards, for in- stance) a tapetum may be developed, but an argentea and choroid gland are never present; all these parts are wanting in Birds. A structure which is homologous with the processus falciformis of Fishes is, how- ever, present in most Reptiles and in Birds. Absent in Hatteria and the Chelonia, this so-called ^^ecten is largely developed in Birds i (Fig. 171), and may extend from the point of entrance of the optic nerve to the capsule of the lens, but In Apteryx the pecten disappears during 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 Wiedersheim, Robert, 1848-1923; Parker, William Newton, 1857-1923. London, Macmillan
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectanatomycomparative
