ROTATORIA OF THE UNITED STATES. 
335 
Internal organs. — The eye lies on the left side of the large brain (fig. 99). The trophi could 
not be studied in detail in the specimens at my command. As noted above, the mucus reservoir 
is divided into two unequal lobes, opening at the bases of the right and left toes, respectively. 
The other internal organs offer nothing of especial importance. 
Measurements. — Length of body, 0.2'i mm.; of toe, 0.15 mm.; total, 0.38 mm. 
History. — This species was described by Gosse, in Hudson & Gosse’s Monograph of the 
Rotifera, as Mastigocerca lophoessa. Figures and descriptions have since been given by Bilfinger 
(1894) and Weber (1898). 
Distribution. — Rattulus Jophoessus Gosse has not yet been found in America. For the oppor- 
tunity of studying it I am indebted to Mr. Charles Rousselet, of London, England, who sent me 
excellent mounted specimens of this rare species. 
In Europe: England and Scotland in pools (Gosse. 1889); Ireland (Hood, 1895); W ur ttemberg , 
Germany (Bilfinger, 1894); Tyrol (Dalla Torre, 1889); Switzerland (Weber, 1898); Lake Nurmi- 
jarvi in Finland (Stenroos. 1898). 
30. Rattulus latus Jennings (pi. vii, figs. 65,66). 
Synonym: Mastigocerca lata Jennings (1894). 
Distinguishing characters . — This species is at once distinguished from all others by the broad 
ovate lorica, coupled with the striking lack of symmetry at the posterior end. This asymmetry 
distinguishes it at once from R. multicrinis Kellicott, the only species that resembles it at all 
in general appearance. 
External features . — The lorica is broadly ovate in dorsal or ventral view, the width being 
about five-eighths of the length. The dorso-ventral measurement is about two-thirds that of the 
width, so that the animal is dorso-ventrally somewhat depressed. When seen in side view the 
dorsal line is a uniform curve from the front of the head to the base of the large foot. The ventral 
line is a similar but less convex curve from the junction of the head- sheath with the lorica to the 
base of the toe, so that the two curves are not symmetrically placed. The lorica is peculiarly 
unsymmetrical in a dorsal or ventral view, for the posterior part of the body, bearing the foot, is a 
thick, truncate cone lying not in the middle line, but on the left side (fig. 66). On the right side 
there is a blunt projection corresponding in position to that bearing the foot, but a little smaller. 
Between it and the left projection is a well-defined notch. 
There is no sign of a ridge or striated area in this species . 
The head-slieath is scarcely marked off from the remainder of the lorica at all; only a slight 
angle on the ventral side marks where it begins. In front the ventral edge of the lorica ends in a 
broad notch, at the bottom of which is a projecting tooth (fig. 65). Dorsally the anterior edge of 
the lorica is a slightly uneven curve, with neither a distinct notch nor a projecting tooth (fig. 66). 
The form of the lorica is not changed appreciably when the head is retracted. 
Corona . — The corona consists of the following parts: (1) A dorsal and lateral fringe of cilia, 
forming about two-thirds the circumference of the head and interrupted in the dorsal middle 
region; (2) at the middle of the dorsal edge a flattened non-setigerous column, truncate at the end; 
(3) below the last, a similar flattened process, bearing at its free end a pair of minute styles. 
Below and at the side of this are (4) a pair of somewhat club-shaped processes curving ventrad. 
At either side of the middle of the coronal disk are (5) four small papillae, the two inner of which, 
at least, bear long setae. These are partially surrounded by (6) an incomplete circle of cilia. 
Antennae . — The dorsal antenna appears as a small tube, reaching the dorsal surface of the 
lorica near the dorsal middle line, some distance from the anterior margin of the lorica (fig. 66, d. a.). 
The lateral antennae are visible in a dorsal view, lying one above each of the two posterior projec- 
tions of the lorica (fig. 66, l. a.). 
Foot . — The foot is very short, scarcely distinguishable as a separate joint. It is borne by the 
left one of the two projections in which the lorica ends. 
Toes . — The main toe (representing the left toe) is a slender, pointed rod, continuing the curve 
of the left side of the lorica. It is about four-fifths as long as the lorica. It is accompanied by 
three short, unequal substyles, the longest (representing the right toe) about one-fifth the length 
of the main toe, the others much shorter. The toe is united to the body in such a way that it can 
be turned to the right, but not to the left. 
