_Mycetes beelzebul_, Gray, Cat. Monkeys Brit. Mus., p. 41 (1870); Schl., Mus. Pays Bas, p. 150 (1876). CHARACTERS.--Black, slightly washed with yellow on the under side of the body and inner side of the limbs; hairs of the body soft, brown at the roots, black at the tips; hands and feet variable, reddish-yellow or reddish-brown, or grey, or black. Upper surface and tip of the tail, spot in front of the ears, and on the knees, reddish-yellow. Length of the body, 17½ inches; tail, 18½ inches. This species differs from the Black Howler (_A. nigra_) by the {198}brown colour of the roots of the hair; and from the species next to be described--the Brown Howler (_A. ursina_)--by the length of the fur and the absence of the reddish-brown tips to the hairs. DISTRIBUTION.--Apparently confined to the Lower Amazon, in the vicinity of Para. HABITS.--The same as those of the species already described. IV. THE BROWN HOWLER. ALOUATTA URSINA. _Stentor ursina_, Humb. and Bonpl., Obs. Zool., i., pl. 30 (fig. nec descr.; 1811). _Stentor flavicauda_, Id. t. c. p. 355 (1811). _Stentor ursinus_, Geoffr., Ann. Mus., xix., p. 108 (1812). _Stentor fuscus_, Geoffr., t. c. p. 108 (1812). _Mycetes fuscus_, Kuhl, Beitr. Zool., p. 29 (1820); Spix, Sim. et Vespert., Bras., p. 43, pl. 30 (1823). _Mycetes bicolor_, Gray, Ann. N. H., xvi., p. 214 (1845); id. Cat. Monkeys Brit. Mus., p. 40 (1870). _Mycetes ursinus_, Is. Geoffr., Cat. Méth. Primates, p. 55 (part., 1851); Gray, Cat. Monkeys Brit. Mus., p. 39 (1870); Schl., Mus. Pays Bas, vii., p. 155 (1876). _Aluatta ursina_, Slack, Proc. Acad. Nat. Sci. Philad., 1862, p. 517. _Mycetes flavicauda_, Schl., t. c. p. 147 (part., 1876). CHARACTERS.--General colour shining yellowish-red, or dark brownish-yellow; hairs rather rigid, black with yellowish tips; hairs of the shoulder ringed with black. When half-grown the limbs and tail are very dark brown, nearly black; tail shorter than the body, olive black, with two yellow lateral stripes. Length of the body, 23 inches; of the tail, 22 inches. {199}YOUNG.--Black, with the tips of the hairs of the body yellowish-brown; base of the tail and the surrounding region reddish-brown. This species is remarkable for great variation in colour. The young at first sight, as Dr. Slack has pointed out, appear to be of an intense black colour, but upon a closer examination, the hairs, more especially those of the back and sides of the head, are found to be tipped with reddish-brown. As the animal becomes older the black gradually vanishes, a yellowish-brown colour appearing in its place, until in the adult the only remains of the black are to be found in a few annulations in the hairs of the shoulders. The skins are an article of commerce, for saddle cloths and saddle coverings. DISTRIBUTION.--The Rio Negro and Upper Amazonia. Mr. Bates remarks that this is the only species seen in this region. V. THE GUATEMALAN HOWLER. ALOUATTA VILLOSA.