514 Wisconsin Academy of Sciences, Arts, and Letters. 
known of this species to warrant the provision of a separate genus 
for it. The external form has been well described by Bilfinger, 
Voigt and Lie-Pettersen, and the mastax by De Beauchamp. 
Genus ROUSSELETIA Harring. 
Notommatid rotifers with short, gibbous, illoricate body, with 
a slight constriction separating head and abdomen; the tail is 
large and collar-like, surrounding the base of the long, unjointed 
foot; the two toes are short and conical. 
The corona is slightly oblique; the marginal cilia are short, 
except on two lateral, auricle-like areas; on the unciliated apical 
plate are two slightly decurved papillae; the mouth is near the 
ventral edge. 
The mastax is virgate and very large; the fulcrum expands 
fan-wise towards the posterior end and is in the transverse plane 
of the body; the rami are large and dome-shaped, without mar¬ 
ginal denticulations; the mallei are simple, curved rods with a 
ventral spur; unci are absent; a rodshaped epipharynx, decurved 
at the ends, is imbedded in the anterior wall of the mastax. 
The retrocerebral sac is large and pyriform; no subcerebral 
glands are present. The eyespot is cervical. 
Type of the genus.—Bousseletia corniculata Harring. 
ROUSSELETIA CORNICULATA Harring. 
Plate XXXVII, figures 1-4. 
'Bousseletia corniculata Harring, Proc. U. S. Nat. Mus., vol. 46, 1913, p. 393, 
pi. 37, figs. 1-3. 
The body is short, moderately stout and gibbous dorsally; its 
greatest width is nearly one third of the total length. The in¬ 
tegument is very flexible, but the outline is quite constant. The 
entire body is colored green by symbiotic zoochlorellae. 
The head and abdomen are separated by a well marked con¬ 
striction. The width of the head segment is nearly equal to its 
length, about two thirds of the greatest width of the body. The 
abdomen increases gradually in width for about two thirds of its 
length and is rounded posteriorly; a short, sleeve-like tail sur¬ 
rounds the base of the foot. The dorsal surface is marked with 
faint longitudinal striations, continued about half way down the 
sides. The foot is relatively long, slightly tapering and without 
