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Page:Popular Science Monthly Volume 32.djvu/118

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THE POPULAR SCIENCE MONTHLY.

Professor S. A. Forbes,[1] in a study of the "Blind Cave Fish and their Allies," is led to review the conclusions reached by Professor F. W. Putnam in his interesting papers on the subject. Professor Putnam brought forth a number of arguments which seemed to him to militate against the views urged by evolutionists that their peculiar characters were adaptive and the result of their cave-life. He was led to the conclusion that the absence of light had not brought about the atrophy of the eyes, the development of special sense-organs, and the bleaching of the skin. In referring to another cave-fish, Chologaster, with eyes fully developed, it was urged that the argument in regard to eyeless fishes could have no weight. In response to this it was answered that possibly Chologaster had not been subjected to subterranean influences long enough to be affected, and this objection was anticipated by urging that we have no right to assume that Chologaster is a more recent inhabitant of the caves, until proved.

The discovery of another species of Chologaster, taken from a spring at the base of a limestone cliff in Illinois, has given Professor Forbes an opportunity to make careful comparisons with the cave Chologaster. He says in regard to it, "The most important and interesting peculiarity of this species indicates a more advanced stage of adaptation to a subterranean life than that of its congeners." Referring to Professor Putnam's arguments. Professor Forbes says that "the discovery of a species of Chologaster, which frequents external waters, of an immediate subterranean origin, supplies all needed proof that the genus either has a shorter subterranean history than Amblyopsis, or, at any rate, has remained less closely confined to subterranean situations; and that in either case the occurrence of eyes, partial absence of sensory papillæ and persistence in color, are thus accounted for consistently with the doctrine of 'descent with modification.'" In this connection it may be of interest to read the curious fact recorded by Mr. S. H. Trowbridge,[2] of the discovery in the Missouri River of a shovel-nosed sturgeon which had the skin growing over the eyes, completely inclosing them. Dr. S. H. Scudder,[3] in a memoir read before the National Academy, brings forward evidence to show that ordinal features among insects were not differentiated in Palæozoic times, but that "all Palæozoic insects belonged to a single order which, enlarging its scope as outlined by Goldenberg, we may call Palæo-dictyoptera; in other words, the palæozoic insect was a generalized hexapod, or more particularly a generalized Heterometabolon." In a memoir on the earliest winged insects of America, embracing a reexamination of "The Devonian Insects of New Brunswick," published by the author. Dr. Scudder replies to some sharp criticisms and objections made by Dr. Hagen, and pertinently says, that "there is no evidence—but the contrary—that Dr. Hagen in his investigations

  1. "American Naturalist," vol. xvi, p. 1.
  2. "Science," vol. iii, p. 587.
  3. "American Naturalist," vol. xix, p. 877.