This genus differs from the preceding only in the characters of some of the teeth. The canine teeth in the lower jaw are longer than their neighbouring incisors; but, as has been pointed out by Prof. St. George Mivart, it is a question whether this generic distinction can be maintained, as an intermediate condition exists in some forms. For the convenience of description the species of this genus have been divided into two groups--(_a_) those with long hair on the head and neck, and (_b_) those with short hairs on the back of the head. The number of species in the latter group is greater than in the former; and they are further divided into those with, and those without, white lips. I. THE SILKY TAMARIN. MIDAS ROSALIA. _Simia rosalia_, Linn., Syst. Nat., i., p. 41, pl. i. (1766). _Midas rosalia_, Geoffr., Ann. Mus., xix., p. 121 (1812). _Leontopithecus rosalia_, Gray, Cat. Monkeys Brit. Mus., p. 65 (1870). _Hapale rosalia_, Schl., Mus. Pays Bas, vii., p. 250 (1876). CHARACTERS.--This is the first species of the long-whiskered and maned group; fur soft and silky; tail equal in length to the body, bushy at the tip; hair round the face and on the back of the neck very long, forming a conspicuous ruff. Face, hands, and feet purple; general colour of the hair golden yellow, more or less red, and glossy. These animals are said to possess an air-sac in the throat, at the back of the _trachea_ (or windpipe), as in _Ateles_. Length, 11 inches; tail, 12 inches. {139}DISTRIBUTION.--The Silky Tamarin is found in the forests of South-eastern Brazil, in the coastal forests of New Granada, and as far north as the Isthmus of Panama. HABITS.--The "Marakina," as this exceedingly beautiful species is often called, lives in small troops, ascending to the slender branches at the tops of the highest trees in the forest. The species is very playful and intelligent. Closely related to the Silky Tamarin, if indeed it is really distinct from it, is the Maned Tamarin (_M. leoninus_, of Humboldt), which inhabits the same region, and is only seven inches in length, exclusive of the tail. "It is named _leoninus_," remarks Mr. Bates, "on account of the long brown mane which depends from the neck, and which gives it very much the appearance of a diminutive Lion." In referring to their intelligence, the same writer continues, "Isidore Geoffroy St. Hilaire relates of a species of this genus, that it distinguished between different objects depicted on an engraving. M. Audouin showed it the portraits of a cat and a wasp; at these it became much terrified, whereas at the sight of a figure of a grasshopper or beetle it precipitated itself on the picture as if to seize the objects there represented."