Harring & Myers—Rotifer Fauna of Wisconsin — II, 515 
joints. The toes are short, conical and acutely pointed; their 
length is about one twelfth of the total length. Only the ventral 
half of the truncate posterior end of the foot is occupied by the 
toes; on the dorsal margin is a minute papilla with a few long setae. 
The dorsal antenna is a small, setigerous pit in the normal 
position; the lateral antennae are on minute tubules, only a short 
distance above and in front of the tail. 
The corona is very slightly oblique; the circumapical band of 
cilia is without any dorsal gap and has laterally two strongly 
ciliated, auricle-like areas. The buccal field is evenly covered 
with very short cilia. On the unciliated apical plate are two 
conspicuous, slightly decurved papillae, resembling those of the 
genus Ploesoma. The mouth is near the ventral margin of the 
corona. 
The mastax is virgate and almost half as long as the body 
proper. The fulcrum is narrow at the base and its sides gradually 
diverge towards the posterior end, enclosing a thin, ovate lamella 
with fanshaped striations; it is unique on account of being in the 
transverse plane of the body. The rami are large and roughly 
triangular in ventral view; the edges are curved towards the 
dorsal side, so that a roughly dome-shaped cavity is formed. The 
mallei are simple, strongly curved rods, with a short spur near 
mid-length; there is no trace of the unci. The epipharynx is rod¬ 
shaped, with decurved ends. The piston is very large and fills 
the entire cavity of the mastax. 
The oesophagus is slender and moderately long. There is no 
constriction between the stomach and intestine. The gastric 
glands, ovary and bladder are normal. The foot glands are long 
and clubshaped. 
The retrocerebral organ consists of a large, pyriform sac, which 
never contains bacteroids; there are no subcerebral glands. The 
ganglion is large and saccate, and the small eyespot is at the pos¬ 
terior end. 
Total length 130/x; toes 10/x; trophi 40/x. 
Rousseletia corniculata occurs in weedy ponds, but never in large 
numbers. It seems to be widely distributed; we have collected it 
at Washington, District of Columbia, at Atlantic City, New Jersey, 
in Oneida and Vilas Counties, Wisconsin, in Fairmount Park, 
Philadelphia, Pennsylvania, and Polk County, Florida. 
