. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Heteropygii. 68 BLIND VERTEBRATES AND THEIR EYES. All these gobies are tenacious of life, especially the blind ones. Several of the latter have been kept in a half-gallon jar of water for several weeks without change of water, and others have been kept several months in confinement in my laboratory. When the water becomes somewhat stale, they frequently rise to the surface and use the water as a plane to which' they attach themselves by means of their ventrals. The earliest date at which I procured young was Octobe
. Cave vertebrates of America; a study in degenerative evolution. Cave animals; Heteropygii. 68 BLIND VERTEBRATES AND THEIR EYES. All these gobies are tenacious of life, especially the blind ones. Several of the latter have been kept in a half-gallon jar of water for several weeks without change of water, and others have been kept several months in confinement in my laboratory. When the water becomes somewhat stale, they frequently rise to the surface and use the water as a plane to which' they attach themselves by means of their ventrals. The earliest date at which I procured young was October 25. The smallest caught at that time is represented in figure 26 b. The covering of the ovarian egg consists first of a finely striate membrane, the zona radiata of all teleostean eggs. Exterior to this is a network of threads with the meshes coarsest at the entodermic pole and forming almost a continuous mem- brane at the ectodermic pole. When the eggs are deposited, the meshwork of threads is stripped off the egg and remains attached to the zona radiata around. Fie. 27. Larval Typhlogobius in its membrane. the micropyle. In the eggs deposited naturally by the females in confinement the threads were wound together to form a cord at the micropylar end of the egg. The cords of many of these eggs were attached to each other, and the eggs thus came to be laid in bunches like those of grapes. In their natural habitat the eggs are fastened by the threads to the lower surfaces of the rocks under which they live, and the membranes are expanded into long club-shaped bags. The yellow of the blind-fish egg is entirely confined to the yolk, which contains many oil globules. The granular protoplasm is opaque. In females with ripe eggs they are frequently to be seen forming a yellow band along the flanks. The eye in the larvse just about to be hatched (fig. 27) is apparently normal. The histology of the adult eye was studied by Ritter, who comes to the follow- ing conclusion: 1. In the sm
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