226 Transactions of the Royal Microscopical Society. 
Who would once have scrupled to say that no monkey has the 
teeth of a rat, or that no rat has the hands of a monkey ? Yet 
the Aye Aye presents the systematizer with either absurdity he 
pleases. 
That every rotifer has a rotary apparatus seemed an absurdly 
self-evident proposition, till Gosses Taphrocampa, Claparede’s 
Balatro and Mecznikow’s Apsilus, showed that Nature will not 
submit even to the widest generalization, and that rotifers may exist 
without the very apparatus to which the whole class owes its name. 
In truth Nature has no such fancies as those Man is ever 
ready to credit her with. She has hut one law — endless variety ; 
and her varieties blend into one another by such fine gradations 
that no natural system of classification can be other than unsatis- 
factory ; doomed to he destroyed and re-cast by every succeeding 
generation of naturalists, as fresh discoveries destroy the value of 
those differences which earlier classifiers have relied upon for 
separating allied forms. 
So long as the tube -makers were represented only by Melicerta 
with its four-lobed disk and pelleted tube, Limnias with its two- 
lobed disk and smooth compact tube ; and (Ecistes with its one- 
lobed disk and irregular fluffy tube, the genera of the Melicertidae 
were comfortably distinct from each other. But the discovery of 
several new species, and the more thorough investigation of the 
older forms, have been steadily bringing all these genera closer and 
closer. 
Gosse, Huxley, Leydig, Williamson, Claparede, and others have 
studied the structure and use of their trochal disks, their internal 
organization, and the nature and mode of secretion of their gela- 
tinous sheaths ; and the result of their labours is that such a 
similarity of structure and habits is seen to run through the whole 
group that Gosse has even proposed to make but one genus of 
them all. 
The new rotifer, which is the subject of this paper, will, I think, 
prove a notable ally in helping to break down the barriers that have 
hitherto separated the genera of the Melicertidae. 
I found it this autumn on a piece of Anacharis given to me by 
Mr. W. Fiddes of Bristol, who had brought it from Sutton Park 
in the hope of getting something worth exhibiting at our Micro- 
scopical Soiree. I placed a bit of the weed at random in a zoophyte 
trough, and on bringing down my inch objective on it, had the 
pleasure of seeing this charming rotifer fully expanded in the very 
centre of the field. It is a Melicerta with a gelatinous sheath, very 
like that which invests the Floscules, and yet with a distinct cha- 
racter of its own. Two striking peculiarities at once catch the eye ; 
namely, the great size and butterfly shape of the trochal disk 
(Fig. 1), and the wonderful length, backward setting, and great 
