MYCETES. 3 
1861, in which he showed, principally from the observations of Herr Deppe and 
M. Sallé, that five genera are represented in Central America, and that Ateles extends 
its range up to the 23rd parallel of north latitude. Eleven years later the same 
zoologist, in a paper “On the Quadrumana found north of Panama” (P. Z.S8. 1872, 
pp. 2-9), enumerated six genera and ten species, tracing their distribution as far as 
was thenknown. This memoir has continued to be our chief authority on the Monkeys 
of the subregion; and further observation has only rendered it needful to modify it in 
some details, as will be seen by comparing the table of the distribution of the genera 
in the Introduction to the present volume with the similar one given by Mr. Sclater 
in 1872. 
Fam. I. CEBIDZ. 
1. MYCETES. 
Alouatia, Lacépéde, Mém. de V’Inst. Nat. iii. p. 490 (1801)*. 
Mycetes, Iliger, Prod. Syst. Mamm. et Av. p. 70 (1811). 
Stentor, Et. Geoffroy, Ann. du Mus. xix. p. 107 (1812). 
Among the American Monkeys which have a partially naked prehensile tail, this 
genus is distinguished by the high pyramidical skull, deep massive mandible, small 
vertical incisors, well-developed thumbs, and above all by the extraordinary deve- 
lopment of the larynx. In this organ the basihyal is much enlarged, and is expanded 
into a bulla or bony capsule, which is lined by a continuation of the thyroid sac, and 
forms the instrument by which the Howling Monkey produces the deep-toned and far- 
reaching shouts from which it derives its name ft. 
Eight or nine closely allied species of Howlers inhabit South and Central America, 
from Paraguay in the south to Guatemala in the north, most of them being confined 
to limited geographical areas. They agree closely in osteological and structural 
characters, but appear to be constant in their differences in colour. The two species 
found in our subregion, to which both are peculiar, may be thus characterized :— 
1. M. palliatus. air of flanks elongated, forming a mantle; colour brown-black 
or black, the long hairs more or less fawn-coloured. 
2. MV. villosus. Hair very long and soft; colour-uniform black. 
* The new generic names here proposed by Lacépéde, in his “‘ Tableau des Divisions &c. des Mammiféres ” 
(often quoted as if it were a separate work), have almost all been entirely disused by subsequent writers, although 
an attempt to revive some of them has been made by Dr. J. H. Slack (Proc. Acad. Philad. 1862). Fortunately 
they are so imperfectly characterized as to come fairly under Rule XII. of the Stricklandian Code; had it 
been otherwise, many well-known generic names would have been ousted by such barbarous titles as Sagouin, 
Aye-Aye, Kinkajou, Hamster, &c. &c. 
+ For a description of this structure see Owen, Anat. of Vert. vol. iii. pp. 598, 599, fig. 471. 
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