List of Crustacea Cladocera from Madison, Wis. 391 



1867. Drepanothrix hamata, Norman and Brady. Monograph of the 

 British Entomostraca belonging to the families Bosminidae, 

 Macrothricidae and Lynceidae. Nat. Hist. Trans. Northum- 

 berland and Durham, 1867, p. 12, description of female, 

 pi. XXII, figs. 5 female, 6, antennule, 7 post-abdomen. 



1867. Drepanothrix dentata, P. E. Mueller. Danmarks Cladocera, p. 

 138. Description of female. PL II, fig. 13, antennule. 



1881. Drepanothrix dentata, Herrick, C. L. Geol. and Nat. Hist. Sur- 

 vey, Minnesota. 12th Report, 1881, 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, " The head not separated from 

 the valves by a depression." 



1888. Drepanothrix dentata, Richard, J. Recherches sur la Paune 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 Charae as the chief living plants. In this zone I have found this 

 cladoceran quite common. It is not confined to it, however, but is met 

 with both inside and outside of this limit. In the marsh proper, how- 

 ever, I have never found it. It is 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 Chydorus, Pleuroxus, Daphnia and most other forms 

 present will congregate on the side toward the light, Drepanothrix hastens 

 away from 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 setae. 



