172 DYSTERIA. 



of its free edge. The broader or dorsal shell (up) is convex 

 toward the eye, and the whole organization lies within its con- 

 cavity, whilst the narrower one (bk, iw) is flat, simply covering the 

 body, and as a natural consequence does not include any part 

 of it. The open space between them is endowed with a row of 

 closely-set, large, vibratile cilia, which differ in size according to 

 their position; those in front (/') being by far the longest, and 

 those along the side scarcely more than half as long; and in 

 addition there is one (/) which, from its great size, has more of 

 the character of a proboscis, and is attached nearly at the ex- 

 treme anterior border of the row. 



It is not an easy matter in this case to determine how much 

 of the one-sided, cilia-bordered furrow corresponds to the disc or 

 vestibule of Epistylis, Stentor, Paramecium, or Pleuronema; nor 

 does it affect the question of the degree of obliquity of the con- 

 formation of this animal, as long as we see that, whatever it may 

 be, either wholly or in' part a vestibule, it is at least extremely 

 oblique, and that it is not possible to view it from any point but 

 that the body appears asymmetrical in relation to it. 



The most striking peculiarity of this creature is its habit of 

 swinging around on a pivot, (pv,) which consists of an ovate or 

 lancet-shaped appendage, of considerable dimensions, that pro- 

 jects from near the posterior end of the body, and in the line of 

 the row of cilia. The pivot possesses perfect flexibility at its 

 base, so that the animal can move over a considerable distance 

 backwards and forwards without disturbing the point. Most 

 of the time it keeps the flat side down when gyrating around its 

 place of attachment, but now and then it turns up on its right 

 edge, and performs its eccentric rotations about the appendage. 

 This is the habit which, as I said before, has impressed some 

 observers with its similarity to the Rotifera. In connection with 

 this, too, it happens that the creature possesses a pair of jaw- 

 like, or rather pincer-like bodies (j) which lie near the entrance 

 to the mouth, and occasionally open and shut like a pair of for- 

 ceps, just, as similar bodies known as the jaws of Rotifers do, 



j 



whilst food is passing between them. Excepting the passage 



