. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Evolution. OO&OO^'^ ^. Fig. 38. Cht'lnf^aster agassizii. (d) Cross-section of Part of Head. (b) Vertical Section through Retina of a Specimen 38 mm. long. (c) Vertical Section tlirough Retina of a Specimen 62 mm. long. Rods, Cones, and Figment Layers omitted. id) Lower part of Iris of the Same Specimen, 62 mm. long. smaller and much less numerous than elsewhere. The sclera and choroid are as in papilliferus, including a pigment mass below the exit of the optic nerve just within the sclera. The optic nerve measu
. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Evolution. OO&OO^'^ ^. Fig. 38. Cht'lnf^aster agassizii. (d) Cross-section of Part of Head. (b) Vertical Section through Retina of a Specimen 38 mm. long. (c) Vertical Section tlirough Retina of a Specimen 62 mm. long. Rods, Cones, and Figment Layers omitted. id) Lower part of Iris of the Same Specimen, 62 mm. long. smaller and much less numerous than elsewhere. The sclera and choroid are as in papilliferus, including a pigment mass below the exit of the optic nerve just within the sclera. The optic nerve measures 24 /x at its point of entrance into the pigment layer of the retina, and it is thus one-fourth smaller in diameter than in papilliferus. The pro])ortionate thickness of the retinal layers as compared with the layers of papilliferus is seen in the table. The maximum thickness in the largest specimen is but 130 fj. as compared with 166 /a in papilliferus. This differ ence is almost entirely due to the thickness of the pigment layer, which is 74 /i in the largest agassizii and 104 /x in the largest papilliferus, leaving a difference of but 6 /A in the other layers. The pigmented layer is, on an average, much thinner. 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 Eigenmann, Carl H. , 1863-1927. Washington, D. C. , Carnegie Institution of Washington
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