. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Evolution. 138 BLIND VERTEBRATES AND THEIR EYES. is not simply a miniature normal eye. The whole eye has collapsed with the dis- appearance of the vitreous humor, and looked at in this light there is no difliculty in the position of the cartilages which have fallen together over the front of the eye. The presence of granular nuclei in front of the eye over the region of the iris has been noted by Kohl in Troglichihys and observed by me. These nuclei are probably the homologucs of the nuclei found in the ligamentum
. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Evolution. 138 BLIND VERTEBRATES AND THEIR EYES. is not simply a miniature normal eye. The whole eye has collapsed with the dis- appearance of the vitreous humor, and looked at in this light there is no difliculty in the position of the cartilages which have fallen together over the front of the eye. The presence of granular nuclei in front of the eye over the region of the iris has been noted by Kohl in Troglichihys and observed by me. These nuclei are probably the homologucs of the nuclei found in the ligamentum pectinatum of Chologastcr. In shape, number, and size the scleral cartilages differ very much. In one instance cartilages extend continuously from the exit of the optic nerve more than half-way over the side and around the front of the eye. In another a single cartilage lies directly in front of the eye, and on the opposite side of the same individual a single cartilage lies behind the eye. The sclera is much more developed than in Chologaster, consisting, aside from the cartilages, of an abundant fibrous Fin. so. Section through the Eye of Amblyapsis speltsus ys mm. long, killed with Chromic Acid and stained with Biondi-Ehrlich's thjee-coior mixture. This is the most highly developed eye seen, 2 mm. and 4. The choroid is a thin membrane closely applied to the eye. It contains a few oval nuclei parallel with the surface of the eye. Pigment cells are few, irregularly scattered, and not at all uniform in different eyes. The pigment cells arc rounded masses usually much thicker than the whole of the choroid in regions devoid of pigment. About the entrance of the optic nerve is frequently a large accumulation of pigment corresponding with the increase in the amount of choroidal pigment in Chologastcr at the same place. Even this mass is not uniformly present. Some- times granular masses interspersed with pigment are found here, which give one the impression of a degenerati
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