THE CROWN ANIMALCULE. 
35 
Ehrenberghs figures of the apparatus in this species seem more 
than usually incorrect j it is hut fan 1 to add, however, that he 
admits his observation to be susceptible of doubt ; and I can 
give my own testimony to the exceeding difficulty of obtaining 
satisfaction as to the real structure of these minute organs. Ac- 
cording to my judgment, formed on many careful examinations, 
and that in many specimens, each of the two mallei or upper jaws 
consists of three curved diverging fingers, whose extremities are 
united by an indented membrane like the foot of a water-fowl.* 
The incus, or lower pair of jaws, consists of two very move- 
able and widely-separated rami, shaped somewhat like a quar- 
ter of a globe, but much flattened, and each furnished with a 
lengthened process, which unites with its fellow to form the 
hinge, without a fulcrum. The uncus is connected with the 
ramus by an elastic ligament, by which means the latter is 
stretched open vigorously, while the teeth of the malleus act on 
the prey imprisoned in the crop. 
Let us now follow the engulphed, but yet vigorous and active 
prey. The crop we will suppose to be nearly full of Monads, as 
I have seen it to the number of a hundred or more ; then we 
perceive how ample is its capacity, for it descends, with the con- 
tained prey, far below the level of the jaws, while the individual 
Monads on which the action of the jaws has been passing, often 
return among their fellows. During fife, and seen in action, 
the incus, or lower pair of jaws, takes the form of a long oval 
box, partially open across the middle, or that of a pair of slippers 
without quarters, placed heel to heel, so as to cross each other 
at that part. The two mallei resemble hands continually 
engaged in tearing apart the two sides of the box, or the toes 
of the shppers, by which action the aperture is alternately 
opened and closed, or rather made to recede and approach. 
The living contents of the crop come successively, but by no 
means regularly, within reach of the jaws, and are dragged into 
* These constitute the uncus, the lower part of which forms a knob, in- 
closed in a muscular mass, which seems to answer to the ordinary manubrium. 
For a full explanation of these terms, and the organs to which they are ap- 
plied, I must refer to the memoir cited in the preceding note. I may say 
here that a general idea of the apparatus of the mouth, which is very complex 
in this class, may be formed by supposing a pair of gardener’s shears, the two 
handles of which are soldered into one, and then bent down at a right angle to 
the blades. Then imagine two claw-hammers to be placed, one on each side, 
working in the blades of the shears, to which each hammer is tied by an 
elastic cord. Inclose the whole in a great rounded vessel, and fasten the 
parts to the interior by muscular bands, leaving an orifice with a tube over 
the blades, and another beneath and behind them, and you have a rough model 
of a Rotifera’s mouth. The shears are the lower jaws [incus), of which the 
blades are the rami, and the united handles the fulcrum. The hammers are 
the upper jaws [mallei), the claw-head of which is called the uncus, and the 
handle the manubrium. The inclosing vessel represents the mastax. 
