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BULLETIN OF THE UNITED STATES FISH COMMISSION. 
the antero-dorsal part of the inastax and widens into the large saccate stomach and intestine. 
Rounded gastric glands are attached to the anterior part of the stomach in the usual way. The 
ovary is an oval plate with large nuclei embedded in its granular substance, and it has generally 
a large maturing egg attached to it. Lateral canals, with flame cells attached, and a contractile 
vesicle are present. The dorsal antenna emerges from a small depression in the head just behind 
the tip of the brain, and the lateral antennae are situated in the lumbar region, on each side of the 
body. The foot emerges nearly ventrally; it consists of two short joints and is furnished with two 
very long, thin, narrow, glassy toes, about half the size of the body in length. The toes are nearly 
straight for about half their length, then they are decurved; one or two very small substyles are 
present at the base of each toe. In swimming the animal moves slowly, as if the small ciliary 
wreath were not powerful enough to move the comparatively large body, and I always found it at 
the bottom of my tanks among the sediment. 
“Length: Total, with toes, sV inch (0.317 mm.); of body alone, inch (0.213 mm.); of toes 
alone, inch (0.105 mm.). Habitat, Sandhurst, Berks.” 
Stenroos (1898) found this species in Lake Nurmijarvi, in Finland, and gives a description 
and figure. Stenroos’s specimens were larger than those of Rousselet, the body shorter and thicker, 
the projection of the lorica back of the foot larger, and the foot consisted of but a single joint, 
instead of two, as described by Rousselet. (This last-named difference probably arises merely 
from a variation in interpretation as to what should be called a “ joint.”) 
15. Diurella helminthod.es Gosse (pi. xiv, fig. 122). 
Synonym: Rattuhis helminthodes Gosse (1889). 
Distinguishing characters.— ‘ Body very slender, especially in front; the width less than one- 
fifth the length; toes without accessory styles at base; brain clear.” (Gosse, 1889, p. 65.) This 
species was described by Gosse from a single dead specimen. He says that it approaches Diurella 
tigris Muller in form, in the slenderness and in the comparative length of the toes, but it is much 
more elongated and the anterior part especially is more slender than in D. tigris Muller. He 
thinks there is a low dorsal ridge, beginning insensibly near the middle of the length and ending 
in an oblique angle near the foot. Gosse thought that no substyles were present, but was not 
absolutely certain of this. Whether or not a tooth is present at the anterior edge, as in D. tigris 
Muller, Gosse does not say. Length to tips of toes, 0.25 mm. ; of toes, 0.066 mm. ; width and depth 
of body, 0.05 mm. 
Glasscott (1893) lists this species from Ireland and states that the anterior part was of the 
same diameter as the posterior. 
Scorikow (1896) has given a description of a rotifer which he identified doubtfully as this 
species, without a figure, but his account adds nothing of importance to that of Gosse. 
Distribution. — Gosse (1889) found D. helminthodes in a pool near Birmingham, England; 
Glasscott (1893) in Ireland; Scorikow (1896) near Charkow, Russia; Wierzejski (1893) in Austrian 
Poland. 
16. Diurella marina Daday (1889) (pi. xiv. figs. 133-126). 
This species was described by its author in the Magyar language, so that I am unfortunately 
unable to make use of his description. His figures are reproduced in pi. xiv. figs. 123-126. 
In a brief note in German, Daday (1890) says that Diurella marina most resembles Diurella 
tigris of Ehrenberg, but is distinguishable from it by the structure of the mastax and the peculiar 
border of the head-sheatli of the lorica. What these peculiarities are must be judged from the 
figures. The figures do not show whether the toes are equal or unequal. 
This species is marine and was found by Daday in the Bay of Naples. 
17. Diurella brevidactyla Daday (1889) (pi. xiv, fig. 128). 
This species, like the last, was described in the Hungarian language, so that I can not use the 
description. In a brief resume Daday (1890) says that this species is distinguished from D. marina 
Daday by the simple anterior edge of the lorica, that its toes are very short, and that its mastax is 
different from that of D. marina. It is likewise a marine species and was found in the Bay of 
Naples. 
