ROTATORIA OF THE UNITED STATES. 
323 
Foot. — The foot is rather sharply set oft' from the rest of the body. The posterior dorsal edge 
of the lorica projects on the left side some distance over the point of attachment of the foot, so 
that the latter can not bend to the left, but bends almost directly to the right (fig 52). 
Toes. — The single main toe (representing the left toe of Diurella) is nearly or quite as long as 
the lorica; the right toe (figs. 50 and 111, r. t. ) is rudimentary and small. The main toe apparently 
does not grow during the life of the animal, while the remainder of the body does, so that in a 
young specimen the toe is as long as the entire body (fig. 51) , while in adult specimens (figs. 50, 52. 
and 111) it is only about three-fourths or less the length of the body. 
Internal organs. — These offer nothing especially noteworthy. The troplii (fig. 51) are very 
unsymmetrical, the left manubrium being lung, stout, and curved; the right one, a slender, straight 
rod about three-fourths the length of the left. 
Measurements. — Length of adult body, 0.2 mm.; of toe, 0.15 mm.; total, 0.35 mm. 
History. — This species was first described by Gosse in 1880, on page 61 of Hudson & Gosse's 
Monograph, vol. 2. Like many of Gosse’s descriptions, the account of this species is somewhat 
inexact, the figure and description not agreeing in all points. It is on account of this inexactness 
in Gosse’s descriptions that I have considered it justifiable to identify the species here described 
with that described by Gosse. The resemblance in general appearance and form of the body is 
great, as will be seen by comparing Gosse’s figure with my fig. 51. But Gosse describes the animal 
as having three spines at the anterior margin of the lorica, each running back some distance as a 
sharp ridge. His figure shows but one of these spines, and no rotifer is known which would answer 
to this description. Gosse probably took the profile of the flaring edges of the lorica for two of the 
spines. 
A more important difference is in the length of the toe. Gosse describes and figures the main 
toe as a little less than half the length of the lorica, while in the species here described it is much 
longer. Gosse’s notes and figures are often inaccurate, however; for example, he states that in this 
species the mastax occupies more than half the body length, while in his figure it does not occupy 
one-third the body length. I have thought it best, therefore, to give this species Gosse’s name, at 
east until one corresponding more exactly to Gosse’s description is found. 
No description or figure of this species, except that of Gosse, has been published. 
Distribution. — In America: Put-in Bay Harbor and East Harbor, Lake Erie; Graveyard Pond, 
Presque Isle, near Erie, Pa. ; near ‘ ‘ The Cottages, ’ ’ Long Point, Canada, on north shore of Lake Erie. 
In Europe: England (Hudson & Gosse, 1889); Ireland (Glasscott, 1893); Wurttemberg, Ger- 
many (Bilfinger, 1892); Gr. Ploner See, Germany (Zacharias, 1893); near Basel, Switzerland 
(Ternetz. 1892); Lake Nurmi jarvi in Finland (Stenroos, 1898); Bohemia (Petr, 1890). 
Also in Ceylon (Daday, 1898). 
20. Rattulus macerus Gosse (pi. v, figs. 53, 54). 
Synonyms: Mastigocerca macera Gosse (1889); Mastigocerca fusiformis Levander (1894). 
Distinguishing characters. — This species is to be known by the elongated fusiform body 
(sometimes a little curved); the toe one-half to two-thirds the length of the body, the short spur 
(figs. 53, 54, sp.) projecting backward from the base of the toe when the latter is bent forward, and 
the single, very small and inconspicuous tooth at the right anterior edge of the lorica. 
External features. — The body is elongated and fusiform, the dorsal surface much more convex 
than the ventral. In some specimens (fig. 53) the body is slightly curved. The head-sheath is 
marked off. as usual, by a slight constriction. It bears at its anterior margin, to the right of the 
dorsal middle line, a small, very inconspicuous tooth. This tooth is very easily overlooked, beirg 
hidden commonly by the fleshy head; it was not observed by Gosse or Levander. What 
corresponds to the ridge or striated area is not strongly marked; in contracted specimens (fig. 53) il 
may be noticed as a broad, elevated area extending backward from the region of the tooth. In 
fully extended specimens it can hardly be seen at all. 
The corona has not been studied. 
Antennce . — The dorsal and lateral antennae are in the usual positions, the former a little 
behind the constriction separating off the head-sheath; the latter on the posterior fourth of the 
lorica, at the sides. 
Foot. — The foot is slender and cylindrical. It bears at its tip a spur, which is described in the 
account of the toes. 
