J. FULLAGAR ON TUBICOLARIA NAJAS. 185 



eggs are to be seen in various stages of development at the same 

 time, yet the movement of the Najas is not obstructed by the eggs, 

 nor are the eggs interfered with by the contracting or expanding of 

 the animal. 



I have remarked that there is a double row of cilia ; this is rather 

 difficult to make out, but I have at times been able to do so, and I 

 see that a correspondent to " Science Gossip," in describing Melt- 

 certa ringens mentions the same fact. The motion of the cilia on 

 the outer edge of the disk appears to go in the direction indicated by 

 the arrows (Fig. 8t), while the inner current appears to move in the 

 opposite direction (as at u.) Fig. 10 is a sketch of the jaws or 

 gizzard, the dotted lines show them open, the dark lines shut. 



I have previously mentioned that the mouth was lined with cilia ; 

 this, in some instances, was very clearly seen, that is, when the 

 Rotifer was more transparent than at other times, which is the case now 

 and then, and also when the animal was bent from the observer. 

 In one particular position the mouth is then very prominent, and 

 the cilia are observed to be very long, and to project some distance 

 from it. At the same time small particles, of what I should 

 suppose to be rejected matter not fit for food, are seen thrown 

 out with some degree of force ; and it is a peculiar trait in the 

 character of Najas that it is enabled, by the action of the cilia, to 

 draw particles towards the mouth with some degree of rapidity, and, 

 at the same time, and by the same agency, to repel and cast off 

 whatever the animal may find unsuited to its wants. 



Description or Plates XVI, XVII, XVIII. 



Fig. 1. — a, mouth ; b, gizzard ; c, stomach : d, lower stomach ; e, intestine ; 

 /, vent ; i, position of egg after extrusion. 



Fig. 2. — g, formation of egg in the body ; h, oviduct. 



Fig, 3. — Egg after extrusion. 



Fig. 4. — Egg four days after extrusion ; 7, first appearance of cilia, and 

 at m, where also the jaws appear; n, two spots. 



Fig. 5. — Elongation of egg ; o, wreath of cilia. 



Fig. 6. — The form taken on escaping from the parent tube. 



Fig. 7. — When first fixed ; r, stomachs seen. 



Fig. 8. — Further development of the ciliated lobes; t, outer current of 

 cilia ; u, inner ditto ; s, commencement of gelatinous tube. 



Fig. 9 — Young, closed. 



Fig. 10. — Jaws of T. Najas. 



