Hcirring and Myers—-The Rotifers of Wisconsin. 635 
between neck and abdomen. The abdomen is broad and oval in 
outline. The tail is not very large; it has a median lobe, rounded 
posteriorly, and two small lateral lobes. The foot is very nearly 
cylindric and obscurely three-jointed; its length is about one 
eighth of the total length. The toes are long, straight, and slen¬ 
der, ending in conical points; their length is about one fourteenth 
of the length of the body. 
The dorsal antenna is a small setigerous papilla in the normal 
position; the lateral antennae are small, short tubules with a few 
setae at the tip; they are somewhat farther back on the abdomen 
than is usually the case. 
The corona is frontal and consists of a marginal wreath of 
cilia, interrupted dorsally and passing in a curve to the lateral 
angles, where it joins an inner circle starting also from the dor¬ 
sal gap; from the angles the marginal wreath continues as a single 
band, closed ventrally and passing immediately below the mouth. 
The buccal field is not ciliated. 
The° mastax is of a modified virgate form, in which the pump¬ 
ing action has been partly lost and the trophi have become adapted 
to the seizure of prey, as the animal is carnivorous. The rami 
have the form of a nearly equilateral triangle in ventral view; 
there are two strong, recurved lateral apophyses for the attach¬ 
ment of the powerful muscles which open the rami. Near mid- 
length they are bent at a right angle, and at this point the left 
ramus has a single, large tooth, which interlocks with two similar 
teeth on the right ramus. There is an elongate-ovate ventral op¬ 
ening between the rami, and a narrow space dorsally, between the 
frontal teeth and the tips of the rami; the inner edges of this 
dorsal extension are minutely denticulate. From the lateral 
apophyses a thin lamella passes in a very complicated curve to 
the dorsal points of the rami, thus limiting the cavity of the mas- 
tax. It should be noted that the only openings in the rami are 
the median dorsal and ventral; the irregularly oval areas on the 
ventral face are merely thin sections of the same material as the 
ribbed structure. The fulcrum is a very broad, subrhomboidal 
plate, slightly rounded posteriorly. The unci consist of a rather 
small, subsquare basal plate with a single, very robust, club-shaped 
ventral tooth; from a point near the middle of the tooth a diago¬ 
nal rib crosses the basal plate to a point opposite the dorsal mar¬ 
ginal rib of the manubrium. At the median dorsal angle of the 
unci there is a very loosely attached small plate of irregular out- 
