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118 THE WATER CABINET. 
siderable force, as the water is again ejected. The quan- 
tity drawn into the body by this hydrostatic action must 
be considerable, since the dimensions of the larva regu- 
larly change with the breathing action, the body becoming 
collapsed when the stream is ejected, and again swelled 
out with the suction that follows. If it be thrown into 
water, tinged with cochineal, and then quickly removed 
again into clear water, the coloured stream will be seen 
to be projected several inches, and with force sufficient to 
propel the creature forward by a series of successive jerks. 
Besides the act of breathing, then, this anal pump has 
locomotive uses; and it also aids the creature in obtaining 
food by drawing minute creatures towards it in a manner 
similar to those animals which are furnished with cilia. 
But the microscope reveals a still more curious fact, 
in the anatomy of this larva, which has been most faith- 
fully described by Kirby and Spence. The under lip, 
when closed, entirely conceals the mouth, and it not only 
retains, but actually seizes, the animal’s prey, by means 
of a very singular pair of jaws with which it is furnished. 
Conceive your under lip (to have recourse, like Reaumur, 
on another occasion, to such a comparison) to be horny 
_ instead of fleshy, and to be elongated perpendicularly 
downward, so as to wrap over your chin, and extend to 
its bottom—that this elongation is there expanded into a 
triangular convex plate, attached to it by a joint, so as to 
bend upwards again and fold over the face as high as the 
nose, concealing not only the chin and the first mentioned 
elongations, but the mouth and part of the cheeks. Con- 
ceive, moreover, that to the end of this last-mentioned 
