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NATURAL HISTORY. 
by a modification of a muscle, which in man and the Chimpanzee, for instance, stretches from 
the top of the bladebone, across the lower part of the neck, to the bone at the base of the tongue 
(the omo-Jiyoid muscle). It lias also two bellies in man, or, in other words, the muscular fibres are 
attached to the bladebone and to the hyoid bone, and there is an intermediate tendon ; moreover, this 
passes through a pulley, so that the obliquely-placed muscle in the lower part of the neck acts straight 
upon the tongue, and pulls it down in a right line. In the Macaques, this muscle has no central 
tendon, and the muscular fibres pass all the distance from the bladebone to the os liyoides at the 
base of the tongue. 
In addition to these modifications where muscle replaces tendon, there are those of several other 
muscles which act on the tongue, the larynx, and on the upper and lower parts of the windpipe, their 
THE COMMON MACAQUE. 
conjoined action being to approximate all these parts. These muscles, which are separate in man, are 
united in one in the Macaques. 
The head of these Monkeys, hanging as it does when they go on all-fours, requires extra support, 
and one of the muscles of the back, which from its square shape is called the rhomb-shaped muscle, 
is especially attached to the occiput, and helps to hold the head up. Another assistant in the move- 
ment on all-fours is a muscle which pulls the bladebone forwards when the animal is walking. It 
springs from the outer processes of the upper bones of the neck (transverse process of the upper cervical 
vertebrae), and is attached to the spine of the bladebone. This muscle is seen in the great beasts of 
prey also, and in the Semnopithcci and Guenons. A similar u wild-beast peculiarity exists in 
the arrangement of the muscles of the hand ; the muscle which extends the little finger and opens it 
is divided, and has greater connections with the fourth finger than in man. The long muscle which 
extends the thumb, and the short one which draws it from the fingers, are not separate in the Macaques, 
but the muscle has two tendons, and thus foreshadows the arrangement which in man and the higher 
Apes gives such perfection of movement to the thumb. 
