246 MECZNIKOW, ON ICHTHYDIUM, ETC, 
as, for example, in Aldertia crystallina ; but most probably 
the absence of jaws in the Ichthydina is a property which will 
always serve as a certain distinction between them and the 
Rotatoria. 
But it is otherwise as regards the other. points put forth 
by Dujardin, since the absence of a stout integument and a 
peculiar kind of contractility cannot in any way be used as a 
systematic character. Strictly speaking, this statement of 
Dujardin is net at all true, because there is no difference 
between the movements of some kinds of Notommata and 
those of Ichthydina. 
I leave the idea of Schmarda, namely, that the Ichthydina 
belong to the Naids, without further notice, because even 
Schmarda himself does not try to prove his view. I am 
quite certain that this view is as worthy of acceptance as the 
supposition that the Rotatoria are stationary annelid larvee.* 
Max Schultze finds other grounds for the separation of the 
Ichthydina from the Rotatoria. He says, ‘ A uniting of the 
Ichthydina with the Rotatoria is impossible, because of the 
want in the former of the vibrating organs on the mouth and 
the back, and of the perfection of the muscles, nerves, and 
water vessels, which are so characteristic of the Rotatoria.” 
Against the truth of the first position of Schultze I may 
advance the presence of cephalic cilia on Cephalidium, and the 
form of the vibrating apparatus in some wheel animals (for 
example, Furcularia, Diglena forcipata, and Notommata), 
where it is represented by a simple vibrating patch which 
lies on the surface of the belly. The other suppositions of 
Schultze are also wrong, because different muscles and 
nerves are wanting just as much in many lower Rotatoria as 
they are in Ichthydina. The nervous system is found in a 
very few Rotatoria. Moreover the water vessels in many 
Rotatoria consist only of contractile bubbles, and are wanting 
altogether in Albertia crystallina, as Schultze himself says. 
We cannot agree with Schultze, that the Ichthydina are 
more nearly allied to the Turbellaria than to any other group, 
and we even believe that our animals bear only a very distant 
likeness to the Turbellaria, that is, to the Annelids. 
Let us try to prove the relationship of Ichthydina with the 
Turbellaria by nearer comparison. As to the properties of the 
body, we cannot fail to remark that the typical flattening of 
the more or less oval body of Turbellaria does not exhibit 
itself in any of the animals belonging to the group of 
* It is Prof. Huxley’s explanation of the morphology of Rotatoria which 
the author rejects. 
