30 THE ROTIFEKA. 



structure : the one pair (the ordinary anteniuB) 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 setfe ; m 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 ventrieose at the hinder part, 

 then abruptly diminishmg. 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 roimded 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 wrmkles, 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. i^achyunis, 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 mcurved, the flexure varying m 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. labiatiis, 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. 

 aurit,a. A long oesophagus loads 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, enclosing many small 

 diatoms and other algae ; while the other half was thrown into close longitudinal 

 wrinkles. Within it were four or five oil-globules of brilliant orange-hue, varymg 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, full of clear embryonic vesicles, passing in a sigmoid curve 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 branchiae 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 ofl", each branchial 

 cord adheres firmly to the epithehal 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 very 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 



