It is called the pelvis, or basin-shaped bone (being very unlike one); its upper edge is formed by the expanded haunch, or ilium bones (ilium, or gut, alluding to the support given by the bone to the bowels), and its lower one by the bones on which men and Gorillas sit, or the hip (the ischium, or hip-bone). In the Gorilla the pelvis is enormous, and the edge of the haunches is long, so as to give attachment to the muscles which enclose the vast digestive apparatus behind and at the side, but it does not form a graceful curve behind and below, for certain muscles which are of great use to man in maintaining the erect posture, and which straighten the thigh in the body, are weak in the great Ape. These muscles originate outside and below the top of the haunch, and when large and strong, require a peculiar shape of bone: they form in man what does not exist in the Gorilla, and that in which the Hottentot Venus glories. But the Gorilla can sit just as well upon a pair of short and expanded hip-bones (ischial tuberosities, in the language of anatomists), and as he has no tail (the bones forming it in other Monkeys being diminished in number and united in a short process), he can do so for a considerable time with comfort. The sitting in the upright position is moderately easy to the Gorilla, and the older ones evidently often do so. They squat and rest their broad backs against a tree, and as this is a very constant and favourite position, they wear a good deal of their back hair off.