32 
The howlers form a remarkable group in which the vocal 
apparatus is modified in a manner such as to pour forth a 
volume of sound so great as to suggest their distinctive name. 
The Mantled Howler ( Alouatta palliatus ), Brown Howler 
( A.fuscus ), Red Howler (A. senicula ), and Black Howler 
( A . niger) belong to this group. 
The Grey Lagothrix ( Lagothrix humboldti') and the 
Black Saki ( Pithecia satanas ) are natives of Brazil. The 
males of the latter species have a thick beard covering the 
lower part of the face and the throat. 
The Ateles or Spider Monkeys are characterized by the 
absence of a thumb; although in several species it is present 
in a rudimentary condition ; they have a prehensile tail, 
lined on the tip with a very sensitive skin, which answers the 
purpose of a hand in suspending themselves from the branches 
of the trees among which they altogether live. They are 
very delicate, and do not long withstand the severities of our 
climate. 
The Black Spider Monkey (. Ateles ater), the Brown 
Spider Monkey ( A . hybridus ), the Chuva ( A . marginatus), 
the Marimonda (. A . belzebuth), and the Black-handed 
Spider Monkey (A. geoffroyi) are usually to be seen here. 
The Brown Capucin ( Cebus fatuellus ), the Weeper Ca- 
pucin (C. capucinus ), and the White-throated Capucin (C. 
hypoleucus ) are all small monkeys of the kind usually trained 
for circus performances and organ-grinders. These, with 
the Ti-ti or Squirrel Monkey ( Saimaris sciurea ), all be¬ 
long to the family Cebidce . 
A rare and little-known member of the Cebidce, a specimen 
of which has been exhibited by the Society, is the Red 
Ouakari (. Brachyurus rubicundus ), from Brazil. 
The Common Marmoset (. Hapale jacchus ), the Black¬ 
eared Marmoset (AT. pencil lata), the Pinche (. Midas ce dipus), 
the Silky Marmoset (J/. rosalia), and Geoffroy’s Mar¬ 
moset (M. geoffroyi) are small and beautiful monkeys from 
the hottest parts of tropical America. They are frequently 
kept as pets, but being of frail constitution, they suffer from 
the slightest approach to cold, and it is hardly possible to 
keep them for exhibition. 
