In a former number of ST. NICHOLAS the largest circus in the world was described, and the curious animal actors were shown in many of their tricks and performances. We now wish to exhibit another circus, the smallest in the world, the performers in which, numbering several hundreds, could all be carried about in a cherry-stone--in fact, a circus of fleas, of such remarkable intelligence that in their various feats they were quite equal to many of the larger trained animals with which we are familiar. But before showing what the flea can do, let us look at its antecedents. We know that it is a wingless fly,--a cousin to the house-flies on one side, and to the crane-flies on the other; and a more knightly-looking little creature you can not possibly imagine. Under the microscope we see it covered with a rich polished armor resembling tortoise-shell. The head is small, and supports two _antennæ_ or feelers, composed of five joints, and between these is the proboscis, a terrible affair. Upon close examination with a powerful glass, what an array of piercing and cutting blades are seen,--long, narrow, transparent knives, each edge armed with a double row of glistening points that extend outward and then are hooked backward! These are known as the mandibles, and fit closely together, concealing another and smaller blade that has a similar but single row of points. Besides all this, there are two cutting-blades; the under edges are as sharp as sharp can be, while the upper are thick and set with bristles. Do you wonder then that the flea is so sharp a biter? On its armored head are two large eyes; and the entire body is seen to be made up of a series of elastic armor-like bands wonderfully jointed, and armed with bristling spines like the steel points on the armor of olden times. The legs are six in number, jointed in so remarkable a manner that they can be folded up one within another. When the flea makes its prodigious leaps, these six legs all unfold at once, hurling the little fellow high into the air. The baby flea is produced from a minute egg that in six days hatches into a tiny worm. In about ten days, the worm changes into a chrysalis, and in twelve days more it appears a perfect flea, ready for warfare upon anything or anybody. Who first discovered that the flea was susceptible to education and kind treatment is not known; but the fact remains that on their small heads there is a thinking-cap capable of accomplishing great results. In the selection of fleas for training, however, the same care must be taken as with human beings, as the greatest difference is found in them. Some are exceedingly apt scholars, while others never can learn, and so it is that great numbers of fleas are experimented with before a troupe is accepted. The Flea Circus here described was exhibited a few years ago and was composed of about two hundred of the most distinguished and intelligent fleas in the entire family.