1911 Encyclopædia Britannica/Howler
HOWLER, a name applied to the members of a group of tropical American monkeys, now known scientifically as Alouata, although formerly designated Mycetes. These monkeys, which are of large size, with thick fur, sometimes red and sometimes black in colour, are characterized by the inflation of the hyoid-bone (which supports the roof of the tongue) into a large shell-like organ communicating with the wind-pipe, and giving the peculiar resonance to the voice from which they take their title. To allow space for the hyoid, the sides of the lower jaw are very deep and expanded. The muzzle is projecting, and the profile of the face slopes regularly backwards from the muzzle to the crown. The long tail is highly prehensile, thickly furred, with the under surface of the extremity naked. Howlers dwell in large companies, and in the early morning, and again in the evening, make the woods resound with their cries, which are often continued throughout the night. They feed on leaves, and are in the habit of sitting on the topmost branches of trees. When active, they progress in regular order, led by an old male. (R. L.*)