Harring and Myers—The Rotifers of Wisconsin. 585 
body as a slight chin. The auricles are rather small, and the 
ciliation is continuous with the corona. 
The mast ax is of the virgate type, with slightly asymmetric 
trophi. The rami are nearly triangular in ventral view and are 
bent nearly at a right angle at the extreme anterior point. The 
right ramus has on its median ventral edge a blunt, knob-like 
projection, which is a continuation of the ventral edge of the ful¬ 
crum; behind this projection it is slightly excavate and then in¬ 
clines gradually toward the teeth of the unci. This section of 
the ramus is finely denticulate. The left ramus has a ventral 
projection similar to, but smaller than, the one on the right ramus; 
it is also more deeply excavate, and the ventral, inclined surface 
is coarsely denticulate and striate on its inner edge. Beyond the 
anterior angle the dorsal portions of both rami are minutely den¬ 
ticulate on their opposing edges. The fulcrum is long, broad, 
and stout; the posterior end is enlarged and curves inward. The 
unci have a single, well developed ventral tooth and a rudimen¬ 
tary dorsal tooth at the edge of a broad basal plate; from the root 
of the ventral tooth to the tip of the torsal tooth there is an 
inconspicuous diagonal rib. The left ramus has four very slender 
pre-uncial teeth attached ventrally to the tip, while the right 
ramus has three much larger teeth in this position. The anterior 
half of the manubria is a very broad, thin lamella, and the poste¬ 
rior half a slender, curved rod. Besting with their anterior ends 
on the inner surface of the rami and meeting dor sally at a point 
somewhat below their tips, a pair of slender, slightly curved rods 
pass diagonally under the anterior ends of the manubria; they are 
imbedded in the walls of the mastax and assist in its support dur¬ 
ing the pumping action. 
The oesophagus is rather short and slender. The gastric glands, 
stomach-intestine, ovary, and bladder are normal. The foot glands 
are fairly long and pyriform. 
The retrocerebral sac is pyriform and moderately large; it 
opens on the corona through a long, tubular duct and is filled 
with bacteroids, which make it appear black by transmitted light. 
The subcerebral glands are long and pyriform, reaching down well 
below the eye-spot, which is at the posterior end of the large, 
saccate ganglion; the glands do not contain bacteroids. 
Total length 250/*; toes 20/* ; trophi 42/*. 
