ROTATORIA OF THE UNITED STATES. 
327 
cylindricus Imhof. Finally, Minkiewicz (1900) redescribed and figured this species under the 
name Mastigocerca hamata var. bologoensis. 
Distribution.— I have found this species in East Harbor, Lake Erie, near Sandusky. Ohio. Speci- 
mens were also sent me by Prof. E. A. Birge from inland lakes in Wisconsin. 
In Europe this species has been recorded as follows: Bayous of the Rhine (Lauterborn, 1893); 
Wurttemberg, Germany (Bilfinger, 1894); Lake Bologoe in Russia (Minkiewicz, 1900); a pond in 
Germany (Zacharias, 1897). 
23. Rattulus capucinus Wierzejski & Zacharias (pi. vi, figs. 59-61). 
Synonyms; Mastigocerca capucina Wierzejski & Zacharias (1893); Mastigocerca hudsoni Lauterborn (1893). 
Distinguishing characters.— This species is at once distinguished from its nearest relative, 
R. multicrinis Kellicott, by the elongated, cylindrical form of the body. From all other known 
species it is distinguished by the large triangular projection of the lorica above, the head, a 
character which it shares with R. multicrinis Kellicott alone. 
External features. — The body is an elongated cylinder, somewhat curved toward the ventral 
side, as shown in fig. 60. There appears to be considerable variation in the proportions of the body. 
Those studied by the author (from Germany, obtained through the kindness of Mr. C. F. Rousselet.) 
were of the proportions shown in figs. 60 and 61; but the figures of Wierzejski & Zacharias (1893) 
show a much shorter animal, while the figure of Lauterborn (1893) is still shorter, and the ventral 
surface forms almost a straight line. The specimens which I have examined agree more nearly in 
their proportions with those found by Levander (1894) and Stenroos (1898) in Finland. The lorica 
seems to have nothing which can be compared with the ridge or the striated area in most Rattulidce. 
The liead-slieath is set off by a marked constriction from the remainder of the lorica. There 
are many longitudinal seams at which the sheath folds when the head is retracted (fig. 59). 
Between these seams the parts of the head-sheath project at the anterior margin, so that the edge 
is crenate. The dorsal part of the head-sheath runs out to a strong triangular point, projecting 
far over the ventral edge of the lorica. This gives the retracted head the appearance of a capucin 
cap, whence the specific name. The whole structure is almost identical with that of R. in ultierinis 
Kellicott. 
Corona. — The corona, according to Wierzejski & Zacharias (1893), is very similar to that 
described above for R. multicrinis Kellicott. There are two central antenna-like processes, the 
more dorsal one being longer, and two lateral processes on each side. There are likewise two dorso- 
lateral semicircular wreaths of cilia. These are shown in fig. 61. 
Antennal. — The dorsal antenna has not been observed in this animal. The lateral antennae 
are in the usual position on the flanks, about half way back from the middle of the body (fig. 60). 
Foot. — The foot is a short, conical structure. It is overhung on its dorsal surface by a roof- 
like backward projection of the lorica (fig. 60). 
Toes. — The main (left) toe is a nearly straight rod about half the length of the body. The 
rudimentary right toe is one-fourth to one-third the length of the main toe, and lies across the 
proximal part of the latter. A small, scale-like substyle lies against the side of the main toe. 
Internal organs . — These call for no special remark, save in the case of the troplii. These, 
according to Wierzejski & Zacharias (1893), are not unsymmetrical. 
Measurements. — Length of body, 0.30 mm.; of toes, 0.125 mm.; total, 0.425 mm. 
History. — This species was described in 1893 by Wierzejski & Zacharias, under the name Mas- 
tigocerca. capucina. In the same year Wierzejski (1893) gave a description (in Polish) and repeated 
the figures given by Wierzejski & Zacharias (1893), while Zacharias (1893) also gave a brief 
description and a new figure. In the same year Lauterborn (1893) described this animal as Masti- 
gocerca hudsoni. A figure and brief description were given by Levander in 1894, and notes by 
Stenroos (1898). 
Distribution. — In America: Lake St. Clair and West Twin Lake, near Charlevoix, Mich. 
In Europe: Gr. Ploner See, in Germany (Zacharias, 1893); bayous of the Rhine (Lauterborn, 
1893); Wurttemberg, Germany (Bilfinger, 1894): Galicia. Austro-Hungary (Wierzejski, 1893): 
Lake Nurmijarvi in Finland (Stenroos, 1898); Lohijarvi-See in Finland (Levander, 1894); River 
Oudy near Kharkow, Russia (Scorikow, 1896); Lake Bologoe in Russia (Minkiewicz, 1900). 
