. Carnegie Institution of Washington publication. EYES OF THE TEXAN CAVE SALAMANDER. 35 the iris and extends into the depth of the vitreous cavity. Apparently on the external half of the iris the pigmented layer has become rolled in and folded upon itself in the interior of the eye, giving rise to a pigment mass over 100 ^ thick. No such mass is present in the left eye. The pigment on the inner or upper half of the iris is as in the younger stages. The choroidal pigment entering the eye is in solid, vermiform strands (fig. 7 b). THE RETINA. The retina of TypJilomolge is much simpler than that
. Carnegie Institution of Washington publication. EYES OF THE TEXAN CAVE SALAMANDER. 35 the iris and extends into the depth of the vitreous cavity. Apparently on the external half of the iris the pigmented layer has become rolled in and folded upon itself in the interior of the eye, giving rise to a pigment mass over 100 ^ thick. No such mass is present in the left eye. The pigment on the inner or upper half of the iris is as in the younger stages. The choroidal pigment entering the eye is in solid, vermiform strands (fig. 7 b). THE RETINA. The retina of TypJilomolge is much simpler than that of Proteus. In the latter all the layers typical of the perfect retina are still distinguishable. In the former the outer reticular layer has entirely disappeared, and the layers between the rods and cones and the inner reticular layer form a mass of cells that are homogeneous as far as ordinary histological methods permit one to determine. There are no- where the slightest evidences of any rods or cones, either in the largest or smallest individual. The nuclei of the outer nuclear, the horizontal, and inner nuclear layers are alike. Miillerian fiber-nuclei have not been distinguished as such. This layer consists of about five series of nuclei and measures 44 ju- in thickness in the smallest (30 mm.), and 48 /*in the largest (90 mm.), specimen; it is between 32 and 48 /j. in the specimen 70 mm. long. The inner reticular layer is thin, but well defined. It is 6 /x thick in the smallest specimen and 16 /A in the specimen 70 mm. long. In section the ganglionic layer forms a U-shaped mass of cells. In the larger specimens it is about 60 /A thick and made up of from five to seven series of cells. The vitreous cavity is a widely flaring, trumpet-shaped structure, with its pointed end reaching to near the center of the eye (fig, 7 a). In the older specimens it is filled by fibers and cellular tissue, apparently continuous with the choroid ingrowth from the pupil (fig. 7 b). The optic
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