The tongue has a horny supplementary under-tongue (_sublingua_) attached beneath it. The stomach is simple, not formed of several compartments. The transverse portion of the great intestine is convoluted in a remarkable manner upon itself, the cæcum also being very large. The main arteries of the arm and leg break up (as in the Sloths) into an immense number of small vessels (called _retia mirabilia_) parallel to one another instead of being simple branching trunks. The long tendons of the muscles for flexing the digits (the {13}_flexor longus digitorum_) differ generally in arrangement from those of the higher Primates. The Lemuroids are of no commercial value to Man. As regards their distribution, the _Lemuroidea_ are now absolutely confined to the Old World, and predominate in the island of Madagascar, where, as M. Grandidier remarks in his magnificent work on that country, there is scarcely a little wood in any district in which they are not found. Indeed, of the nearly seventy species of Mammals inhabiting that island, thirty-five, or one-half, are Lemurs. Members of the family also occur across the whole of the neighbouring continent of Africa, but their northern range does not reach quite to the tropic, whereas it extends some few degrees beyond it in the Southern Hemisphere. Elsewhere they are confined to the forests of the Oriental region. More or less isolated in Southern India, they re-appear in China, and spreading south to Java they reach as far east as Celebes and the Philippine Islands. The present isolation of the Lemurs in two such distant areas--in Africa and Madagascar and some of the Mascarene Islands on the one hand, and in Southern India, China, Ceylon, and the Malayan Islands on the other--has been considered by some naturalists as weighty evidence in favour of a former land connection between these distant regions. Though so restricted in their distribution at the present day, this group was more widely represented in past ages of the world's history, as we shall have to point out later on. Abundant fossil remains prove that they lived in Europe and in North America, where to-day they are quite unknown. The _Lemuroidea_ are almost entirely arboreal, and seldom come to the ground, except the Sifakas, which then progress {14}on their hind legs by a series of bounds, holding their hands over their head in a ludicrous fashion. Most of them are nocturnal, or crepuscular, sleeping the greater part of the day in holes or on a branch of a tree coiled up in a ball. Their food consists chiefly of leaves, fruits, honey, birds' eggs, and birds, or any small animals they can pounce upon. The Lemurs now living are divided into three families. The Aye-Aye and the Tarsiers, on account of their very special characters, constitute each a distinct family--named _Chiromyidæ_ and _Tarsiidæ_ respectively--while the True Lemurs form the third, the _Lemuridæ_, to which all the remaining forms belong. THE AYE-AYES. FAMILY CHIROMYIDÆ.