SUBORDER DUPLICIDENTATA Two pairs of upper incisors always present, with enamel extend ing round to their posterior surfaces. The suborder includes the Picas, Hares and Rabbits.
The family Ochotonidae includes the Picas or Tailless Hares, which, in addition to the absence of a tail, are further distin guished from the hares and rabbits by the much smaller ears and smaller size of the body ; the number of different forms is very great, the Picas being widely distributed over the mountainous parts of Central Asia and extending into South-eastern Europe and North America.
The family Leporidae contains the hares and rabbits, in which the hind-limbs are elongated, the tail short and recurved, and the ears long. Premolars .. The typical genus, Lepus, occurs in Europe, Asia, North America and Africa. The species and races are very numerous, some 19 different forms being found in Europe alone. In N. India there is a hare which is considered to
represent a distinct genus Caprolagus; C. hispidus differs from all true Lepus in having an entirely brown-coloured tail and the ears being shorter than the head; in Lepus the ears are at least as long as the head, and the tail white beneath. The genera Nesolagus and Pentolagus are nearly allied to Caprolagus. The "Cotton-tails" of North and South America belong to the genus Sylvilagus. The Red Hares of South and South-east Africa, Pronolagus, more resemble rabbits in form, and usually have bright red tails. The Common Rabbit belongs to the genus Oryctolagus, distributed originally over North Africa and South ern and Central Europe; distinguished from Lepus by its shorter ears and hind limbs, and the fact that the young are born blind.