List of Crustacea Cladocera from Madison, Wis. 383 



ber at various localities near Madison. It lives in clear water among 

 weeds, and a dredge which can be dragged through the weeds and not 

 merely above them is needed in order to secure it. With the cone- 

 dredge it is not difficult to obtain 20 to 100 specimens. The same may- 

 be said of such bottom forms as Ophryoxus and Drepanothrix. 



Sars speaks feelingly of the difficulties which beset one who attempts 

 to view this powerful and obstinate cladoceran from the side. If a life- 

 box is used and a trace of % P er cent, of solution of osmic acid in water 

 is added to the water containing the animal, there will be little trouble 

 in turning it on its side. After the poison begins to act, it is best to at- 

 tempt turning the animal by rotating the cover of the life-box. If left 

 to die undisturbed the antennae are usually expanded while an irrita- 

 tion applied to it while alive causes it to fold the antennas along its 

 sides, when it can readily be turned into any position. 



Species 6. Latonopsis occidentalis, sp. nov. Plate XIII. Figs. 1-5. 



In 1888 G. O. Sars* established the genus and species Latonopsis 

 australis for a new form of the Sididce raised by him from mud obtained 

 from Australia. I have found here a second and closely allied species of 

 this new and remarkable genus, and have succeeded in finding males 

 which did not developein Sars' aquaria. 



Latonopsis, Sars, is closely ailed to Latona, Sars, and may be charac- 

 terized as follows: 



latonopsis, Sars. 



Impression between head and thorax slight or wanting. Labrum 

 devoid of plate-like expansion. Antennule with a long, plumose, straight 

 or curved flagellum, articulated to the basal part. Antenna with simple 

 rami, the superior ramus bi-articulate, the inferior tri-articulate, as in 

 Daphnella. Heart concave dorsally, truncate anteriorly, the aorta arising 

 on the ventral side. Shell-gland with three long branches. Male (of 

 L occidentalis, Birge, at least) with simple copulatory organ, and hook 

 on first leg. Antennule long, slightly curved, armed with fine teeth re- 

 sembling in general the antennale of Sida, but having a median projec- 

 tion near the base. Color of both species yellowish-transparent. 



SPECIES. 



a. Fornices absent. Antennule shorter than anterior margin of 



head. L. australis, Sars. 



b. Fornices present. Antennule longer than anterior margin of 



head. L. occidentalis, sp. nov. 



* Sars, G. O. Additional notes on Australian" Cladocera raised from Dried Mud. Chris - 

 tiania 1888, pp. C-15. PI. I. Christiania Videnskabs Selskabs Forhandlinger 1888. No. 7. 



