Harring and Myers—The Rotifers of Wisconsin. 575 
are very stout and somewhat asymmetric. The fulcrum is of 
moderate length, straight, and slightly tapering towards the tip, 
which curves inward and is formed of two lamellae joined in a 
Y-shaped section serving for the attachment of the muscles of the 
piston. The right ramus has four transverse grooves directly be¬ 
low the teeth of the unci, all very shallow with the exception of 
the first, ventral groove, which is quite deep and separates off a 
broad, subsquare, lamellar tooth, curving to the left; the margin 
of this tooth, as well as the entire inner edges of both rami, is 
striated, but not denticulate. To make room for the broad, 
curved tooth of the right ramus, the left ramus is excavate ven- 
trally; it has three additional transverse grooves, in which the 
teeth of the mallei rest; at its highest, anterior point there are 
five or six small teeth, the remainder of the inner edge being 
striated like that of the right ramus. The right uncus has a 
strong, club-shaped ventral tooth, followed by two slender teeth 
and a curved, diagonal rib crossing the uncus from the lower ven¬ 
tral edge to the tip of a fourth, dorsal tooth; the left malleus has 
one tooth less. At the point of the first tooth of the right uncus 
there are four minute, slender supplementary teeth; the left uncus 
has four similar but much larger teeth. These supernumerary 
teeth are not very firmly attached to the unci and are detached 
quite readily when the tissues are dissolved in potassium hypo¬ 
chlorite; they are found in quite a number of species of the genus 
and may possibly be considered a local specialization of the sub¬ 
uncus or a remnant of it, as the subuncus proper is not present 
in the virgate mastax. The manubria are nearly straight, with 
a broad, subsquare lamella at their upper ends. A pair of curved 
rods, attached to the inner surfaces of the rami and terminating 
below the tips, assist in supporting the walls of the mastax dur¬ 
ing the pumping movement. The oesphagus is long and slender. 
Stomach and intestine are only indistinctly separated. The 
gastric glands are small and rounded. The ovary is slightly 
elongate transversely to the axis of the body and of somewhat ir¬ 
regular outline. A small bladder is present. The foot glands 
are club-shaped and rather small. 
The retrocerebral sac is pyriform and reaches beyond the 
mastax; the subcerebral glands are only half the length of the 
sac. The sac presents the usual vacuolate appearance; a few 
opaque granules are scattered through its substance. The glands, 
on the contrary, are crowded with bacteroids, especially at their 
