Harring and Myers—The Rotifers of Wisconsin. 581 
anterior transverse folds are not very conspicuous. The abdomen 
increases very slightly in width for about one half of its length 
and then tapers very gradually to the tail, which has a single, 
broad, rounded lobe. The two joints of the foot continue the 
general outline of the body without any abrupt reduction. The 
toes are rather short, about one twentieth of the total length, 
slender, conical, and acutely pointed. 
The dorsal and lateral antennae are minute setigerous papillae 
in the normal positions. 
The corona extends down on the ventral side nearly one third 
of the length of the body; the post-oral portion projects from the 
body as a very small chin. The auricles are small, but strongly 
ciliate and continuous with the corona. 
The mastax is of the virgate type and slightly asymmetric. The 
fulcrum is very long, slender, and slightly tapering; the posterior 
end is expanded and incurved. The rami are approximately tri¬ 
angular in ventral view and bent at a nearly right angle at the 
extreme anterior point; near their base there is a blunt projection, 
bifid at the tip and continuing the ventral line of the fulcrum. 
Behind this projection the rami are slightly excavate, and the 
inner margin of the right ramus is concave and minutely denti¬ 
cular, while the left has a convex margin with six or seven small 
teeth, continued diagonally downwards on the convex lamella as 
fine striae. The alulae are unusually large and project outwards 
and downwards from the rami proper. The unci have an ap¬ 
proximately subsquare basal plate with a large ventral tooth and 
a very slender second tooth immediately behind it; a diagonal 
rib crosses the basal plate from the external end of the second 
tooth to the anterior dorsal angle. The left uncus has three 
small pre-uncial teeth at the tip of the principal tooth, and the 
right has four similar, but slightly smaller and more pointed 
teeth. A short and nearly straight lateral supporting rod is em¬ 
bedded in the walls of the mastax. The manubrium is broadly 
expanded anteriorly as a subsquare plate, continuing as a long, 
slender rod, slightly incurved at the tip. The oesophagus is very 
long and slender, and the gastric glands are fairly large. The 
stomach and intestine are separated by a well marked constriction. 
The ovary is normal and the bladder large. The foot glands are 
pyriform and rather small. 
The retrocerebral organ is unusually well developed. The sac 
is more than one third as long as the body; the posterior portion, 
