ROTATORIA OF THE UNITED STATES. 
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cilia about the dorsal and lateral margins of the corona (a). (2) Two smaller arcs of cilia, one on 
each side of the mastax (5) . When the mastax is protruded far out, it appears that these two arcs 
are actually borne on the tip of the mastax itself (fig. 48, b). (3) A long, blunt central process (e) 
borne on the dorsal margin of the corona. (4) A short, pointed central process (c) just below the 
last. (5) On each side of the last named two straight, slender processes ( d ) , the inner one in each 
pair being pointed, the outer one blunt. All these processes were well described by Kellicott 
(1897). The corona resembles considerably that of Rattulus lotus Jennings, and is still more like 
that of R. capucinus Wierz. & Zach. , as described by Wierzejski & Zacharias (1893). 
Antennee. — The dorsal antenna is nearly or quite in the middle line, just in front of the line 
separating the head-sheath from the remainder of the body (fig. 55). The lateral antennae are 
situated one on each side, about half way back from the middle of the body (fig. 55, /. a.). 
Foot. — The foot forms a short cone, tapering rapidly to the toes. 
Toes . — The main (left) toe is not quite so long as the lorica, and is nearly straight. The right 
toe is rudimentary, forming a short spine which lies obliquely across the base of the left or main 
toe. Between this and the main toe is a minute substyle, and there is a similar one at the left of 
the base of the main toe. 
Internal organs . — The eye is attached to the large brain some distance in front of its posterior 
end. The trophi (fig. 57) are stout and almost symmetrical, a condition found in only a few of 
the Rattulidee, but occurring in R. capucinus Wierz. & Zach.. evidently the nearest relative of 
R. multicrinis Kellicott. The mastax can be protruded far out from the lorica. as shown in fig. 56. 
The remainder of the internal structure calls for no special remark beyond the statement that this 
species furnishes an excellent opportunity for a study of the characteristic internal organs of the 
Rattulidee., these being particularly well displayed in the broad body of this animal. 
Measurements. — Length of body, 0.18 to 0.20 mm.; of toe, 0.09 to 0.10 mm.; total, 0.27 to 
0.30 mm. 
History. — This species was described by Kellicott in 1897, from Sandusky Bay. Lake Erie. It 
has not been reported by anyone else until the present time. 
Distribution. — Rattulus multicrinis Kellicott has thus far not been found elsewhere than in 
Lake Erie. I found it in East Harbor, Lake Erie; Kellicott (1897) in Sandusky Bay, Lake Erie. 
22. Rattulus cylindricus Imhof (pi. vn, fig. 62-64). 
Synonyms: Mastigocerca cylindrica Imhof (1891); Mastigocerca setifera Lauterborn (1893); Mastigocerca hamata 
Zacharias (1897); Mastigocerca hamata, var. bologoensis Minkiewicz (1900). 
Distinguishing characters. — This species is to be distinguished by the median anterior curved 
hook which hangs down over the anterior opening of the lorica (not always visible) ; by the longi- 
tudinal folds of the head-sheath when the head is retracted; by the very long, prominent dorsal 
antenna (not always visible) ; by the nearly cylindrical body, usually highest a little in front of the 
foot; by the long toe, nearly or quite equaling, or sometimes exceeding, the length of the body, and 
by the habit of carrying the egg attached to the posterior end of the lorica. 
External features . — The body is nearly cylindrical in form, but in many specimens it rises 
gradually toward the posterior end, its highest point lying just in front of the foot (fig. 62). Here 
the body falls off steeply to the foot (figs. 62 and 63) . In some specimens, however, the body tapers 
gently backward to the foot (fig. 64) . It was from such specimens, only still more slender than fig. 
64, that Zacharias’s species Mastigocerca hamata was described. The dorsal line shows in side view 
a characteristic slight depression just behind the dorsal antenna, rising again back of this region. 
The ventral line is very nearly straight. 
The head-sheath is not sharply set off from the rest of the lorica, though there is usually a 
gentle, shallow constriction where the lorica passes onto the head. The head-sheath has longi- 
tudinal folds similar to those found in Rattulus multicrinis Kellicott and R. capucinus Wierz. & 
Zach. By means of these folds the anterior opening of the lorica can be quite closed (fig. 62) . The 
median dorsal part of the anterior edge projects as a triangular point (as in the two species just 
mentioned), but in R. cylindricus Imhof the tip of this point is prolonged to form a hook, which 
bends downward over the anterior opening of the lorica (fig. 62, 64). This hook is thickened jxist 
distad of the place where it joins the lorica. It. cylindricus Imhof is distinguished by this hook 
from all other species of Rattulidee. It is important to note, however, that when the head is fully 
