. Animal biology. Zoology; Biology. Fig. 170. Fig. 171. Fig. 170.—An isopod, Oniscus asellus Linnaeus. (From Paulmier, in Bull. 91, N. Y. State Mus., by the courtesy of the. New York State Museum.) X 3. Fig. 171.—An amphipod, Hyalella dentata (Say). (From Paulmier, in Bull. 91, N. Y. State Mus., after Smith, by the courtesy of the New York State Museum,.) X 6. appendages. They are found in all waters, a common fresh-water form, Hyalella (Fig. 171), being one of the most generally distributed of all North American animals. Amphipods are also found on the beach between tide marks, where, because
. Animal biology. Zoology; Biology. Fig. 170. Fig. 171. Fig. 170.—An isopod, Oniscus asellus Linnaeus. (From Paulmier, in Bull. 91, N. Y. State Mus., by the courtesy of the. New York State Museum.) X 3. Fig. 171.—An amphipod, Hyalella dentata (Say). (From Paulmier, in Bull. 91, N. Y. State Mus., after Smith, by the courtesy of the New York State Museum,.) X 6. appendages. They are found in all waters, a common fresh-water form, Hyalella (Fig. 171), being one of the most generally distributed of all North American animals. Amphipods are also found on the beach between tide marks, where, because of their power of jumping, they are termed beach fleas. 302. Entomostraca.—Entomostraca (en to mos' tra ka; G., entomos, cut in pieces, and ostrakon, a hard shell) are, generally speaking, of small size but they occur in numbers that can hardly be realized. It has been estimated that on the average each cubic meter of water in the small Wisconsin lakes contains about forty thousand individuals. Cladocerans have been observed in a small alkaline lake in Cherry County, Nebraska, in such numbers that the whole lake, when seen from a distance, was of a red color. Entirely around the shore was a windrow of these animals, cast up by the water, a foot wide and from an inch to two inches in depth. A wide-mouthed bottle filled by one dipping from the water of the lake at the shore was about half filled with the organisms after preservation of the material and on settling. The group (Fig. 172) includes Cladocera (kla dos' er a; G., klados, sprout, and keras, horn), also known as water fleas; and Copepoda (ko pep' o da; G., kope, oar, and podos, foot), some of which are parasitic on fish, being called fish lice. A third order is Ostracoda (6s tra ko'da; G., ostrakodes, having a shell), which are inclosed in bivalve shells and look like miniature Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - co
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