ot THE ROTIFERA. 
Family XV. CATHYPNADA. 
[Body znclosed in a lorica, open at cach end, of two plates; the dorsal more or less 
elevated ; the ventral nearly flat, the two divided by a deep lateral longitudinal sulcus, 
covered with flexible membrane ; toes two, or one, always exposed. 
This is a well-marked, easily recognised, and compactly coherent group, the two 
divisions of the lorica, and their connection, readily identifying its members, notwith- 
standing the diversity in toes. The appearance, viewed from behind, reminds one of a 
pair of bellows, if we only imagine the upper board arched instead of flat; the leathers 
representing the lateral sulci. The toes, in two of the genera, are two, furcate; in the 
others there is but a single toe: yet the form, position, and use of these organs are so 
exactly identical, and yet so peculiar, that the genera cannot be dissociated. An ample 
brain, descending into the occiput, carries a single eye, usually conspicuous. The trophi 
are large, the mallei much more developed than the incus, virgate. 
All the genera are marked by a common habit, which is not found elsewhere. One 
will rest on the tip of its toe (or toes), and having bent down the whole body, remain 
motionless, and as if asleep, for a long interval, the whole fore-parts retracted. Then 
it will seem to awake, and languidly swing round the body, first to the one side, and 
then to the other, without letting go its moorings, and without protruding its head; and 
then, perhaps, go to sleep again. Or it may rouse itself into activity, and begin to 
grope away among the floccose, or glide deliberately off, soon coming again to anchor. 
Five species were known to Ehrenberg, who placed the two with fureate toes in the 
genus Huchlaus, with which, howeyer, they have no close affinity P.H.G.] 
Genus CATHYPNA, Gosse, gen. noy. 
[GEN. CH. Lorica sub-circular horizontally, usually much arched vertically ; 
lateral inangulation wide and deep ; toes two, furcate. 
The characters by which the species of this genus are distinguished are sometimes 
minute, and even obscure, yet constant; the shape assumed by the toes, and especially 
by the extreme points of these organs, demanding attention. In one group they are 
narrow, parallel-sided, like a carpenter’s rule; in another, much widened in the middle, 
with the sides curving to the point: the former I call rod-shaped, the latter blade-shaped. 
The former, too, do not taper gradually to the tip, but are abruptly narrowed with a 
right-angle, so as to make a sensible shoulder, whence the point descends as a marked 
claw. And this may be only on one edge, or on both edges; the toe being one-shouldered 
or two-shouldered.—P.H.G.] 
C. tuna, Ehrenberg. 
(Pl. XXIV. fig. 4.) 
Euchlanis luna 5 : : Ehrenberg, Die Infus. 1838, p. 462, Taf. lvii., fig. 10. 
[SP. CH. Dorsal and ventral plates of lorica swb-cqual, occipital edge crescentic ; 
toes rod-shaped, two-fifths as long as lorica, clawed ; the claw one-shouldered, one-fifth 
as long as toe. 
The lorica, broadly ovate in horizontal outline, ending in front by a crescentic exca- 
vation, and in rear by a small sinus between two points, and the toes, very narrow, 
parallel-edged, generally carried in contact, with short, sharp claw-tips, may easily serve 
to identify this common species. The dorsal and ventral plates are of nearly the same 
form and curvature; high and deep behind, they come into contact in front, at least at 
the lateral edges, which project in two acute points. During the long retractations of 
the fore-parts, the lorica may be considered shut by this contact. When activity is 
resumed, the plates separate, and a broad head protrudes, the front of which is truncate, 
