. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Evolution. DEVELOPMENT OF THE EYE OF AMBLYOPSIS. 153 optic cavity, led to the mass of ganjrlionic cells (fig. 62 c). This condition of the choroid fissure and its relation to the interior of the eye leads me at this point to say a few words concerning the general structure of the eye. In the description of the eye of the adult I considered that the central ganglionic mass was the result of the collapsing of the eye with the disappearance of the vitreous body and cavity. I was justified in this conclusion by the pro
. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Evolution. DEVELOPMENT OF THE EYE OF AMBLYOPSIS. 153 optic cavity, led to the mass of ganjrlionic cells (fig. 62 c). This condition of the choroid fissure and its relation to the interior of the eye leads me at this point to say a few words concerning the general structure of the eye. In the description of the eye of the adult I considered that the central ganglionic mass was the result of the collapsing of the eye with the disappearance of the vitreous body and cavity. I was justified in this conclusion by the process of degeneration going on in the eye of Typhlomolge, Typhlkhthys, and Tvpkloqobitis. Whatever may have been the eVhfig. ~ Fig. 62. (a) Anterior Face of Transverse Section of Left Eye of Larva 5 mm. long. Sections run obliquely in such a wav that Right Eye is cut first, series beRinning in front. Divergence from Spherical Outline is due to Pressure of Brain on Proximal Face and Epidermis on Distal Face. (6) Anterior Face of Transverse Section of Left Eye of Larva 6 mm. long. No Lens in connection with this Retina. (c) Parasagittal Section of Eye of Larva 6 mm. long, showing Ventrally Choroid Fissure represented by space between Pigmented Layers and Vitreous Cavity represented by Shallow Depression on Ventral Face. Retina differentiated into Ganglionic. Inner Reticular, and Nuclear Layers. (rf) Anterior Face of Transverse Section through Right Eye of Larva, mm. long. (c) Horizontal Section through Middle of Eye of Larva, 7 mm. long, showing Choroid Groove. phylogenetic process in Amhlyopsis, it is evident that ontogenetically the mass of cells does not arise as imagined. It appears from the embryos that the condition of the adults arises more as the result of a contracting of the retinal area without a cor- responding decrease in the size of the eye as a whole than as the result of the col- lapsing of a vesicle followed by the coalescence of
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