The whiptail (_Mastigocerca carinata_) (_Fig. 2_) is another delicate pretty little creature, and, like the skeleton, is encased in a glassy shell. It has a long, tapering, spine-like foot, or, more properly speaking, a toe which is attached to a very short foot by means of a flexible joint which allows free motion. You often will find him in company with the Skeleton, and they seem to vie with each other in performing strange feats. The Whiptail, if possible, looks even more comical than the Skeleton when it stands on the tip of its long toe, a toe which is longer than the entire length of the body, now bending over and nibbling at the plants, now whisking around as if looking and inquiring into some passing object, then sailing through the water with a graceful, easy motion beyond sight. _Brachionus pala_ is also a lovely creature encased in a delicate transparent shell. It is considerably larger than the Skeleton or Whiptail, and is just visible to the unassisted eye. If you drop it in a phial of clear water and hold it up to the light, you can distinctly see it gliding through the water like a revolving white speck. A moderate power of the microscope reveals its beauty. The shell is swelled at the sides, and narrow at the mouth, and round over the back, while the under side is flat. [Illustration: LARGE ROTIFER.] Like the Skeleton and Whiptail, the head of the little Brachion is seen protruding from the upper part of the shell; but instead of one wheel this charming little creature has two, and nothing can be more lovely than a sight of these fast revolving wheels, like two beautiful crowns. The reason the wheel looks so strikingly beautiful in _Brachionus_ is owing to the long cilia which is longer in this genus than in other genera of this great family. The foot of _Brachionus_ is more curious than that of the Skeleton. It is telescopic, and the little animal has the most perfect control over it. He can draw it within the body so that it looks like a ball, and again quickly thrust it out and whisk it around in all directions like a tail. It has two short toes at the end which can be separated or brought together at pleasure. And he can firmly anchor himself by the toes and stretch forward, showing you the great length of the foot. Now he rolls from side to side without letting go his hold and performs other strange feats, and all the while the wheels are rapidly revolving, he has stopped his headlong career through the water and has settled down to get his supper. _Fig. 3_ represents one of the largest rotifers with which I am acquainted. I have never been able to find a description or engraving of it in any work on microscopy. But it is probably well known to microscopists, for it has a wide range. I have found it in New Hampshire, New Jersey and Florida.