Building Apparatus of M. ringens. By F. A. Bedwell. 221 
setae, as shown in Fig. 6, and which lies between the two hooks 
and a little above them. Still, however, we have the striking fact 
that all these three organs are, when the animal is feeding and 
making the pellet (see diagram), situated on the opposite side of 
the animal to that in which the pellet organ is placed. But this 
is what happens: When the pellet is ready the animal turns 
round and deposits it at the spot with which this pimple of setae 
was in contact at the moment before the animal began to turn. It 
does it so quickly that before you have got over the agitation and 
surprise which its unexpected and rapid change of position causes 
you, the act, like a conjuring trick, is over, and the animal is in its 
old position again, with an empty pellet organ hard at work at a 
new brick. It is not always easy to give the animal under a high 
power sufficient room to be quite at its ease, and failing that ease it 
is apt to lay the pellet anywhere, but when quite comfortable and 
at home in its trough, the above results will, I believe, be obtained ; 
and it will be found, as a rule, usually to make its pellet on the 
opposite side of the case to the point at which it deposits it. We 
have thus traced the progress of the pellet from its inception to its 
ultimate deposit, and I will now venture to call attention to some 
points of interest arising out of the above observations when con- 
sidered in connection with other forms of Rotifera. 
Mr. Cubitt’s recognition of Limnias annulatus is most interest- 
ing and valuable. The enpimpled shield with which it gauges and 
regulates the beautiful case that it builds is at once the analogue of 
the spines and pimple of setae in M. ringens ; but I would call 
attention to this fact, that L. ceratophylli has also its shield-like 
instrument and in a corresponding position. Whenever that form 
is seen retiring into its case, its favourite attitude will be found to 
be as in Fig. 7 ; the hard line from a to b in that figure is 
always undeviating in form, and it arises from the presence there of 
the hard shield in question. The shield is seen again in a front 
aspect at Fig. 8, and it acts in two capacities, for when the 
animal retreats, it fills up the mouth of the tube, and serves for an 
operculum , while when the animal is expanded it helps to mould 
the case. The main chin in L. ceratophylli , and over which the 
“ waste ” passes, answers to that in M. ringens, and has a rough 
receptacle underneath in the place where M. ringens has the pellet 
organ. Here it secretes fluid and rough particles which trickle 
over the main chin, and with these it “ rough casts ” its tube on the 
outside, and “ stuccoes ” it smoothly on the inside ; to do the former 
operation it leans over in the attitude which Punch’s victims assume 
at the final slaughter in that eventful history, and then roughly rubs 
on the outside the secreted fluid and coarser particles ; but to do 
the latter it adds the same substance on the inside of the tube, and 
then smooths it down with the shield in question, much as the 
VOL. XVIII. n 
