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 Drepanotlirix. 
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 per 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 antennae 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. 
r 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 occidentalism 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.fJAdditional notes on Australian Cladocera raised from Dried Mud. Chris 
tiania 1888, pp. 6-15. PI. I. Christiania Videnskabs Selskabs Forhandlinger 1888. No. 7. 
