Harring and Myers—The Rotifers of Wisconsin . 587 
moderately deep, ventral, transverse groove, in front of which there 
is a short, broad, lamellar tooth, projecting obliquely towards 
the left. The ventral portion of the right ramus is denticulate 
and striate from the transverse groove to the anterior bend. The 
left ramus is excavate ventrally, opposite the denticulate margin 
of the right ramus. The unci are nearly symmetrical; each has 
two prominent teeth; to the larger, ventral tooth of each ramus 
there are attached two fairly large pre-uncial teeth. The basal 
plate of the unci is rounded dorsally and has three slender, ob¬ 
lique ribs crossing it, differently spaced on the two unci. The an¬ 
terior ends of the manubria are expanded into very broad, thin 
lamellae; the posterior section is slender and curves slightly for¬ 
ward at the extreme end. Under the upper ends of the manubria, 
and starting from the dorsal tips of the rami, are two slender, 
strongly curved rods, imbedded in the walls of the mastax and 
aiding in its support during the pumping action. The oesophagus 
is of moderate length and very slender. The gastric glands, 
stomach-intestine, ovary, and bladder are normal. The foot 
glands are small and slightly club-shaped. 
The retrocerebral organ consists of a very large, clear, vacuolate 
sac, nearly circular in outline and strongly compressed dorso- 
ventrally; no subcerebral glands are present. The eye-spot is 
at the posterior end of the large, pyriform ganglion. 
Total length 300 /a; toes 12/x; trophi 35/x. 
Notommata lenis is common In weedy ponds all over the United 
States, at least wherever we have been able to make suitable col¬ 
lections. 
This species is readily recognizable by the divided terminal 
foot joint and the double dorsal antenna. 
Notommata Placida Harring and Myers, new species 
Plate XLII, figures 3-6 
The body is fusiform and slender, its greatest width being 
about one fourth of the total length. The integument is very 
flexible, but the outline is fairly constant. It is a very trans¬ 
parent animal. 
The length of the head segment is nearly equal to its width, 
or about two thirds of the greatest width of the body; the neck 
