In some wheel animalcules there is a pair of these spurs, and the very remarkable wheel animalcule drawn in Figs. 35 and 36 has six large processes which, though much bigger, appear to be of the same nature. Of these four are seen in Fig. 35, namely, _d.l._, the dorsal limb, _v.l._, the great ventral limb, and _l.l._^1 and _l.l._^2, the two lateral limbs of the right side, all of them carrying fanlike groups of fringed hairs. They are moved by very powerful muscles, and strike the water with energetic strokes, so as to cause the little owner to dart through it. This jumping or darting wheel animalcule is called "Pedalion," and was discovered and described by Dr. Hudson. It is so astonishing and wonderful a little beast, that when Dr. Hudson sent me some alive in a tube by post in 1872, soon after he had discovered it, I could not believe my eyes, and thought I must be dreaming. It is very like the young form of Crustaceans known as a "Nauplius" (see tail-piece to the present chapter) in having (what no other wheel animalcule has) great hollow paired limbs moved by _striated_ muscular fibre, carrying fringed hairs only known before in Crustaceans (crabs, shrimps and water fleas), and striking the water violently just as do those of the Nauplius. And yet all the while it has on its head a pair of large ciliated wheels which serve it just as do those of the common Rotifer. No Crustacean, young or old, has this "wheel-apparatus" nor any vibratile "cilia" on the surface of its body. Pedalion possesses an astounding "blend" of characters. Fig. 35 shows, besides the "paddles" or "legs" (of which two on the other side of the animal are not seen), the broad and large wheel-apparatus W (within which the right eye-spot _r.e._ is seen), and a little lobe (_p_) called the "chin" lying just below the mouth (_m_). The big leg (_v.l._) and the pair on each side (_l.l._^1 and _l.l._^2), of which that on the right side only is seen, end in beautiful fringed hairs, which are only seen elsewhere in the Crustacea (water-fleas and others). Those on the lateral limbs and the great ventral limb (Fig. 36) are set in two groups of four on each side of the free end of the limb, whilst those on the dorsal leg (_d.l._) are apparently not so numerous. I have corrected the drawings, Figs. 35 and 36, by reference to actual specimens kindly given to me by Mr. Rousselet. [Illustration: FIG. 37.–The Rotifer _Noteus quadricornis_–to show its curious four-horned carapace–from which the wheel apparatus, _wa_, emerges in front, and the tail, _t_, behind; somewhat as the head and tail of a tortoise emerge from its protective "box" or carapace. The ridges on the horney covering of the Rotifer recall the horney plates of the tortoises and turtles.]