A long time ago in biology lessons, children were told that hares and rabbits belong to the rodent detachment. At the sight of a rabbit, which constantly with great pleasure, something gnaws, intensively moving his jaws, this did not cause any doubt. The rodent detachment is very extensive, about half of all types of mammals belong to it. These are representatives of both the families of the chinchilla, and porcupine, and the Nodrians, as well as beaver, squirrels, tushka, mouse and many, many others. But in 1912, Zaitsev was expelled from the rodent detachment, though not all teachers are still in the know. So why did this happen, because they are so similar?