98 THE ROTIFERA. 
suggest that Cathypna is Monostyla with the toe cleft through the middle, or that 
Monostyla is Cathypna with its two parallel toes soldered into one.—P.H.G.] 
M. tunanis, Hhrenberg. 
(Pl. XXYV. fig. 2.) 
Monostyla lunaris D : ‘ ° Ehrenberg, Die Infus. 1838, p. 460, Taf. lvii., fig. 6. 
(SP. CH. Lorica broadly ovate, the dorsal plate round and greatly elevated, the 
ventral nearly flat ; both in front projected into wide, triangular, flattened points, be- 
tween which the edge is deeply excavate ; toe straight, rod-shaped ; claw protruded 
between two slender spines. 
The gibbous lorica descends abruptly before it is produced into the wide clear 
triangular lobes in front. And there seems no noticeable difference in outline, either of 
the lobes or of the intervening sinus, between the dorsal and the ventral plates. For, 
in retraction, these are very firmly appressed, with a common outline; so that no 
change of position, and no focusing, makes the eye cognizant of more than a single, 
somewhat thickened, crescentie line. The general figure is so elevated that it is more 
than half a sphere, if we neglect the inangulation of the lateral suleus, which, in this 
species, is not deep. The foot-bulb appears to lie in a hollow of the ventral plate; it is 
wide and kidney-shaped behind, where the straight-edged, rod-like toe is articulated. 
This terminates in a slender acute claw, not with a rectangular shoulder; but with 
a pair of fine points, between which the claw is, as it were, imbedded. Herr HKck- 
stein describes certain appearances, which he interprets of the thickened lorica- 
structure, for strengthening the foot against the violent strains endured as the animal 
throws itself to and fro. He also depicts certain pale-red specks and excessively fine 
lines, going upwards from the claw, which he would connect with the nervous system, 
as well as with the mucous glands. ‘The rotatory organ is simple, but almost retired, 
so that only a slight elevation with a single seta projects out of the lorica. When it is 
extended, we discern two great lobes, which overlap the lorica-edge on each side, over- 
reaching each other dorsally, but ventrally running off into the buccal orifice” (Lbid.). 
A specimen in my possession, anchored by the toe to the glass of the live-box, threw 
itself vigorously into all possible positions, for twenty-four hours, without once removing ; ! 
all that time, so far as observed, active in this special way, but close shut-up. The 
movements, indeed, though constant, were not incessant, but very forceful, spasmodic, 
and sudden. In general the animal is clear and colourless: of this specimen, the whole 
body was stained of a yellow-brown hue, like sherry wine, so deep, while yet clear, that 
no definition of viscera was possible. Yet the red eye was now and then defined, and, 
under direct sunlight, came out very rich, and of a deep crimson hue. The great tri- 
angular lobes of the lorica, being very thin, were quite colourless and glass-like.— P.H.G.] 
Length. When extended, ;}, to 7}, inch. Habitat. Woolston; Sandhurst; 
Thames, near Reading; Snaresbrook (P.H.G.): mostly in pools: not uncommon. 
M. cornuta, Ehrenberg. 
(Pl. XXV. fig. 1.) 
Monostyla cornuta : : é ; Ehrenberg, Die Infus. 1858, p. 459, Taf. lvii. fig. 4. 
(SP. CH. Lorica ovate, moderately depressed, the front shallowly incurved ; toe 
somewhat blade-shaped, the claw without a distinct shoulder. 
This species is very much like MW. lunaris, so as, when retracted, scarcely to be dis- 
tinguished from it except that the anterior dorsal edge of the lorica is slightly less 
incurved. It is smaller, and rather more oval in outline; in the act of extruding the 
1 During the latter part of the time, however, it became very sluggish, and less willing to move and 
jerk about. 
