596 Wisconsin Academy of Sciences, Arts, and Letters. 
slight expansion of the cloaca. The foot glands are very small 
and pyriform. 
The retrocerebral organ reaches in this species its extreme 
development. At the end of a very slender, tubular duct, one 
third as long as the body, there is a very large, pyriform, vacu¬ 
olate sac, containing bacteroids in large numbers, especially at 
the margin, and strongly compressed dorso-ventrally; the combined 
length of sac and duct is more than one half of the entire length 
of the animal. The subcerebral glands are short, reaching but 
little beyond the posterior end of the ganglion, where the large 
eye-spot is situated. 
Total length 325-350/*; toes 12-14/*; trophi 75/*. 
Notommata saccigera is common in submerged or very wet 
sphagnum, but it does not occur in ponds unless strayed from 
its normal habitat. 
This species is readily recognized by its stout, truncate body 
and very short foot and toes, as well as by the remarkably de¬ 
veloped retrocerebral sac. It seems improbable that the animal 
here described is identical with Gosse’s, but it agrees fairly well 
with Ehrenberg’s rather meager description. 
NOTOMMATA SILPHA (GoSSe) 
Plate XLY, figures 1-7 
? Notommata forcipata Gosse, Hudson and Gosse, iRotifera (1886) 2: 
23, PI. 18, fig. 1; not Notommata forcipata Ehrenberg, 1838. —Mon- 
tet, Rev. Suisse Zool. 23 (1915): 321. —Weber and Montet, Cat. 
Invert. Suisse, fasc. 11 (1918): 115. 
Biglena silpha Gosse, Jour. Royal Micr. Soc. 1887: 2, PI. 1, fig. 2; 
Hudson and Gosse, Rotifera, Suppl. (1889), p. 30, PI. 31, fig. 22. 
Notommata silpha Harring, U. S. Natl. Mus. Bull. 81 (1913): 79. 
The body is elongate, fusiform, and very slender; its greatest 
width is about one sixth of the total length. The integument is 
very flexible, but the outline is fairly constant. It is a very 
transparent animal. 
No anterior folds are present to indicate the boundaries of the 
head and neck; the body is nearly parallel-sided for about two 
thirds of its length; posteriorly it is much reduced and wrinkled. 
The tail is very small and has only a single, rounded lobe. The 
