Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume VIII (1888-1891)
Birge, Edward A.
List of crustacea Cladocera from Madison, Wisconsin , pp. 379-Plate XIII ff. PDF (7.9 MB)
MM <-? I o , 4- IzA -.1a r, List of Crustacea Cladocera from Madison, Wis. 391 1867. Drepanothrix hamata, Norman and Brady. Monograph of the -British Entomostraca belonging to the fmles Bosminidae, Macrothricidae and Lyrp~ceidae. Nat. Hist. Trans. Northum- berland and Durham, 1867, p. 12, description of female. pl. XXII, figs. 5 female, 6, anten~Aule, 7 post-abdomen. 1867. Drcpanotlnrix dentata,-P. E._-Mueller.. Danmarks Cladocera,,p. 138. Description of female. P1. II, fig. 13, antennule. 1884. Drepanothrix dentata, Herrick, C. L. Geol. and Nat. Hist. Sur- vey, Minnesota. 12th Report, 1884, p. 73. Description from P. E. Mueller. Plate C, fig. 14, antennule, from P. E. Mueller. In the description of the genus the word '- not " should be erased in the first sentence, "1The head not separated, from the valves by a'depression.". 1888,. 'Drepanothriax dent ata, Richard, J. Recherches sur la Faune des Eaux du Plateau Central. Clermont, 1888. Mention only. The references given above show that this rare species occurs in Den- mark, Scandinavia, Great Britain and France. I have found it here in both sexes and in considerable numbers. Sars' description is accurate, as is that of Norman and Brady. The vas deferens opens in front of the terminal claws without any prolongation of the base into a penis. D. dentata is found in Lake Wingra at a depth of from 5-10 feet. It is most abundant in a particular zone of depth in that lake where the weeds of the marshy margin cease and those of the deeper water have not come in abundantly.' Here is a stretch of bottom a few yards in width composed chiefly of broken up snail shells and vegetable debris and with a few Oharac as the chief living plants. In this zone I have found this ,cla&oceiran-qiite~ommon.---xuitnotu confined to it, Uowever A,, Utime-- with both inside and outside of this limuit. In the marsh proper, how- ever, I have never found it. It Ais a bottom-haunting form and is there- fore difficult to obtain in large numbers. Under some conditions it is markedly repelled by light. If a por- tion of the bottom with this and other Cladocera is placed with water in a watch glass and the whole exposed to strong light as from a lamp, Drepanothrix will at once hurry to the side remote from the source of light. While (Jhydors,' Pleuroxus, Daphrnia and most other forms present will congregate on the side toward the light, Drepanothrix hastens awyfrom it in an awkward scramble. The sabre-like setae from which its name is derived are its chief organ of locomotion. These it uses much as a boy uses a pair of sticks to propel his sled over the ice. It can swim fairly well in the open water, but is hampered by the weight and stiffness -of these seta3.
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