30 THE ROTIFERA. 
structure: the one pair (the ordinary antenn@) seated on the occiput, the other on the 
hinder part of the trunk, one on each side. Each tentacle consists of a tubular column, 
which has a thickened extremity, whence issues, in the anterior pair, a brush of 
divergent sete ; in the posterior, a single seta; all of great length and tenuity. The 
lumbar tubules are much more slender than the occipital, but are twice as long ; and 
the increase to the terminal knob is much more gradual. 
The general form is sub-cylindrical, becoming more ventricose at the hinder part, 
then abruptly diminishing. But this form is subject to constant alteration, as the 
animal is ever lengthening or shortening, swelling one point, and contracting another. 
A very curious appearance is presented by the two sides at intervals. There is, near 
the middle of each side, a portion of the outline, which is now and then thrown into 
folds,—not constrictions of a rounded saccate body, as usual, but presenting the exact 
appearance of a single thin tissue, the edge of which is thrown into sharp, minute, and 
close-set wrinkles, like those of a frill of crimped muslin. The appearance is very fre- 
quent, seldom lasting more than a minute or two: not peculiar to one individual, but 
common and characteristic. I cannot explain it. The body is contracted into a true 
tail, which is of a thick sub-cubical form, corrugated with strong folds of the skin, like 
that of C. pachyurus, presently to be described, but smaller. Below this is a small foot, 
bearing a pair of furcate toes, short, taper, and drawn out to excessively slender points, 
often slightly incurved, the flexure varying in different examples. The frontal cilia ap- 
pear to be seated on slight eminences. ‘The face projects into a channelled protrusile 
lip, whose edges are ciliated; agreeing both in shape and structure with the like organ 
in C. labiatus, but not nearly so large (figs. 2a, 2b). The brain is 3-lobed, composed of 
three pyriform ovate sacs; the outer two clear, the middle one shorter, and turbid or 
almost opaque, with a broad red eye lying transversely across its upper part, in shape 
like a shallow lens. The trophi are large and distinct, of the form seen in Notom. 
aurita. A long esophagus leads to an ample alimentary canal, on which are seated a 
pair of kidney-shaped gastric glands. In the specimen which I have delineated (and I 
have observed it in others), the alimentary canal formed a great bag, one side of which 
was smooth and expanded, a most delicate transparent tissue, enclosmg many small 
diatoms and other alge; while the other half was thrown into close longitudinal 
wrinkles. Within it were four or five oil-globules of brilliant orange-hue, varying in 
size, the light refracted through which made very attractively beautiful objects, as the 
focus was ever and anon changed. ‘The ovary takes the form of a long and slender 
band, fall of clear embryonic vesicles, passing in a sigmoid curye from near the gastric 
glands to the bottom of the cavity. At its hinder extremity was an ephippial egg, covered 
with transparent spines, broad-based, much curved, much like the prickles of a rose, of 
whose development Dr. Hudson has given an interesting account (loc. cit.). Just above 
this was another smaller egg, maturing and already opaque. The undeveloped portion 
of the ovary is speckled all over with minute light-refracting dots. The branchie take 
the ordinary form of slender, somewhat twisted cords, probably tubular throughout, 
beginning apparently at the front face, by many attenuate ramified channels, with 
doubtless open ends, to receive the influent water for respiration ; and terminating each 
on one side of a large contractile vesicle, occupying the hinder end of the visceral cavity. 
Each branchia has attached to it by a slender stem a pear-shaped bag, which hangs 
free in the cavity, at about mid-body ; and, a little below this, an ovate enlargement, 
which is sessile by its whole side. The contractile vesicle takes a globose form when 
full; when it is seen to have a number of very minute clear glands (?) scattered over 
its surface. I found the period of filling, between one contraction and the next, to be 
just three minutes. At the point where the pear-shaped bag is given off, each branchial 
cord adheres firmly to the epithelial lining of the skin; but is free above and below that 
point. I searched carefully, but vainly, for any vibratile tags in the course of either 
branchia. But, in one I saw, in a yery slender offshoot, close to the attachment of the 
pear-shaped bag, which yet was not a ‘‘tag,’’ a vibration exactly similar to that of a 
