. Elements of geology : a text-book for colleges and for the general reader. Geology. Fig. 420. Fig. 421. Figs. 420 and 421. -Devonian Trilobites: 420. Dalmania punctata, Europe, frons, Europe. 421. Phacops lati-. Fig. 422.—Wing of Platephemera an- tiqua, Devonian, America (.after Dawson). Insects.—We have already seen (page 326) that a very few insects (cockroaches and scorpions) have been found in the Upper Silurian. We treated these as anticipations. In the Devonian, for the first time, they become somewhat abundant; and, as was to be expected, are found in connection with the abundant land
. Elements of geology : a text-book for colleges and for the general reader. Geology. Fig. 420. Fig. 421. Figs. 420 and 421. -Devonian Trilobites: 420. Dalmania punctata, Europe, frons, Europe. 421. Phacops lati-. Fig. 422.—Wing of Platephemera an- tiqua, Devonian, America (.after Dawson). Insects.—We have already seen (page 326) that a very few insects (cockroaches and scorpions) have been found in the Upper Silurian. We treated these as anticipations. In the Devonian, for the first time, they become somewhat abundant; and, as was to be expected, are found in connection with the abundant land vegetation of that time (Fig. 422). The Devonian, and, indeed, all the Palaeozoic hexapod insects, belong to one family, which has been called by Scud- der Palaeodictyoptera (old netted-winged), a generalized type connecting the Neuropters and the Orthopters. A chirping organ is believed to have been found in some. If so, it implies also an organ of hearing in these early insects. Fishes.—The grand characteristic of the Devonian is the introduc- tion here of a new dominant class—Fishes—and of a new department, and that the highest, to which man himself belongs—the Vertebrates. This is, indeed, a great step in the progress of life. It is necessary, therefore, to treat these somewhat fully. Commencing far back in the Upper Silurian, few in number, small in size, and of strange unfishlike forms, with the opening of the De- vonian fishes greatly increased in size and number, until the waters fairly swarmed with them. Never since have fishes apparently been more abundant, of greater size, or better armed for offense, and espe- cially for defense. And yet all the species, genera, and even families then existent, are now extinct. Not only so, but tyj^ical fishes—Tele-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1892
