The vampire rises in the air by means of a wide flattened membrane connecting the whole of the limbs and tail, the thumb of the fore-paws and the hind-feet alone being left free. This membrane, though wonderfully delicate, is furnished with minute blood-vessels. It also possesses a system of nerves of the most exquisite power of sensation, which enables it to fly rapidly among the boughs and foliage, avoiding all impediments even in the darkest hours of night. The vampire can run along the ground and climb trees by means of the sharp hooks on the fore-paws. They sleep, however, like ordinary bats, hanging by their hind-feet--being thus able at a moment's notice to take to flight. Of the other species, some have the fur of a blackish colour, some of a ruddy hue. When flying, the larger ones wheel heavily round and round, somewhat in the manner of a pigeon, so that they may easily be mistaken for birds. Although they live largely on insects, they also greedily devour fruits; indeed, some species live chiefly on them. Bates opened the stomach of several, and found them to contain a mass of pulp and seeds of fruit, mingled with a few remains of night insects. On comparing the seeds taken from their stomachs with those of cultivated trees, he found that they were unlike any of them: he concludes, therefore, that they resort to the forest to feed, coming only to human habitations in the morning to sleep, where they find themselves more secure from animals of prey than in their natural abodes in the woods. PART THREE, CHAPTER TWELVE. QUADRUMANA. MONKEYS. The American monkeys consist of two chief families,--the Cebidae, and the Midas or Marmosets--which are again separated into thirteen genera, consisting of about eighty-six species, greatly diversified among themselves. In America neither Pithecidae or Lemurs are found: they exclusively inhabit the Old World. The Cebidae have thirty-six teeth; the Marmosets possess but thirty-two: three of them, however, are pre-molar, as are three of those of the Cebidae, thus distinguishing them both from all the forms of the Old World. The Marmosets are a low type of apes--their brain being smooth, and they having claws instead of nails; but from their intelligent-looking countenances, and their gentle, playful disposition, they appear to have as much sense as the larger apes.