Harring & Myers—Rotifer Fauna of Wisconsin — II. 447 
body as a fairly prominent chin. The auricles are moderately 
large and the ciliation continuous with the corona. 
The dorsal antenna is a large, circular papilla with a shallow 
central depression bearing a minute tuft of setae; the lateral an¬ 
tennae are minute tubules with a few long setae in the normal 
positions. 
The mastax is virgate and slightly asymmetric. The fulcrum 
is long and moderately stout, tapering slightly towards the poste¬ 
rior end, which is somewhat enlarged and incurved. The ventral 
portion of the rami is roughly semicircular; at the apex there is 
on the left ramus a single, blunt tooth, interlocking with two sim¬ 
ilar teeth on the right ramus. The dorsal portion of the rami is 
not denticulate. There is a narrow opening between the ventral 
edges of the rami, beginning above the inconspicuous basal 
apophysis of the right ramus and limited anteriorly by the apical 
teeth; the edge of the right ramus opposite this opening is smooth, 
while the left has about 8 or 9 minute, close-set teeth or denticles. 
The alula of the left ramus, which is somewhat longer than the 
right, ends in a needle-like, slightly curved spur, which is char¬ 
acteristic for this species. The unci are asymmetric and have only 
one well developed tooth. The left uncus has a subsquare basal 
plate with a linear rudimentary tooth crossing diagonally from 
the base of the ventral tooth to a point close to the two parallel, 
rudimentary teeth at the dorsal margin. Close to the ventral tooth 
are two very small teeth, which are reduced to little more than 
the clubshaped points; between these and the diagonal tooth there 
is an additional, blunt, marginal tooth. The right uncus has a 
strongly curved, rudimentary tooth limiting the basal plate on 
the dorsal side; the diagonal tooth does not project beyond the 
margin of the basal plate. Following the ventral tooth are three 
rudimentary teeth, of which only the middle one can be traced be¬ 
yond the margin of the basal plate. Four accessory teeth, gradu¬ 
ally decreasing in size, are attached to the point of the left uncus; 
the right has three similar, but more slender teeth. The manubria 
are nearly straight, with a broad, subsquare basal plate; the poste¬ 
rior ends are slightly incurved and decurved posteriorly. A pair 
of supporting rods are imbedded in the walls of the mastax be¬ 
hind the posterior edges of the dorsal branch of the rami; their 
dorsal ends are slightly expanded and upcurved The piston is 
large and muscular, filling the entire cavity of the mastax. There 
