In this group, while the sense of smell is very perfect, that of hearing is less acute than in the other Sub-families; and that of touch conspicuously blunt, both in the fingers and toes, which are chiefly climbing and not tactile and prehensile organs, as they are in the corresponding limbs of the Anthropoids. The female never produces more than one young at a birth.
The convolutions of the brain are few, but they are more complicated than in many of the South American Monkeys. In very young individuals the cerebellum is more covered by the cerebrum than it is in the adult.
{ 93}The species of this Sub-family are confined to the island of Madagascar. Our knowledge of their general characters, anatomical structure and habits, is very complete, through the researches, both in the field, of M. Grandidier, and in the study, of Prof. Alphonse Milne-Edwards. These results are published in their magnificent "Histoire de Madagascar," to which the reader is referred for fuller information.
The _Indrisinæ_, on account of their superior organisation, and especially their relatively large brain, are considered to be the highest of all the Lemuroids. They are essentially arboreal. If they come to the ground they sit upright on their hind-legs, and progress by jumps, holding their arms above their heads. They are easily tamed, and become gentle in confinement; but they are not very intelligent. The Endrinas "never manifest in any very marked manner," so MM. Milne-Edwards and Grandidier tell us, "the passions that affect the Apes so vividly; their countenance, almost as immobile as that of an herbivorous or carnivorous animal, exhibits neither anger nor pleasure. In captivity they do not seek to be caressed; they appear neither to become attached to their master, nor to take interest in anything about them." Many of their actions, however, and the peculiar sounds they often utter, recall those of Monkeys.
Some of the species are diurnal and others nocturnal.
The Sub-family has been divided into three genera, _Avahis_ with one species; _Propithecus_, with three species, and _Indris_ with a single species. All its members are remarkable for the extraordinary amount of variation in the coloration of their fur.