LOCOMOTION OF ANIMALS ON SOLIDS. 177 



recent observations be correct, an almost perfect erect posture and gait can be 

 temporarily maintained, without any support from the anterior limbs. In 

 continuous and rapid progression, however, even this animal leans forward, 

 and shambling along, supports the weight of the fore-part of the body upon its 

 long anterior extremities, touching the ground alternately with the back of 

 the knuckles of one or other hand, and moving therefore in a half-biped, and 

 half-quadruped, mode of progression. Neither in the gorilla, orang, or chim- 

 panzee, does the skeleton exhibit that perfect adaptation to the erect posture 

 which is seen in man. The feet, though entitled, from their function, to the 

 designation of hands, as implied by the title Quadrumana, are, nevertheless, 

 anatomically constructed after the manner of the human foot, and not after 

 the fashion of the hand. But the foot of the ape is far less perfectly adapted 

 to bearing weight than that of man. The tarsus, metatarsus, and phalanges, 

 are proportionally narrower and longer ; this narrowness is due partly to the 

 general slenderness of the four outer metatarsal bones and their phalanges, 

 but also to the altered size, position, and form, of the great toe, which ceases 

 to be the largest toe in the member, and is no longer placed parallel with the 

 other toes, but is very much shorter arid smaller, stands inwards from the 

 rest, and in these respects, as well as in its form and opposability to the other 

 toes, closely resembles a thumb ; in the orang, it ceases to possess a long 

 flexor muscle. Moreover, the os calcis, in most of the apes, is small, less pro- 

 jecting, straight, and somewhat raised from the ground ; the arch of the foot 

 is less pronounced, and it is so articulated with the leg, that it is not fairly 

 applied to the ground by the sole, but, more or less, by its outer border. The 

 foot of these creatures, indeed, is not a hand, but rather a grasping or prehen- 

 sile foot ; and, in certain men, this character, as manifested by the slight op- 

 posability of the great toe, is not entirely absent. In descending the scale, 

 the foot is still more slender and prehensile, the great toe is further reduced in 

 size, has no independent action, and the foot departs more and more from its 

 human character, ultimately being adapted only for mere clasping, as in the 

 spider monkeys. Besides this, in the Quadrumana, the bones of the leg are 

 more or less bowed ; and in the ordinary position of the tibia, femur, and 

 trunk, in standing, these segments of the animal's frame, are placed at angles 

 to each other, and do not rest in the form of an erect perpendicular column ; 

 the surfaces of the knee-joint are comparatively small ; and the entire lower 

 limb is not only weaker, but altogether shorter, than in man ; whilst the arms 

 are lengthened, in various proportions, in different species, so as to enable 

 them to reach the ground. The pelvis is narrower, longer, and weaker. The 

 vertebral column does not present that marked threefold curve which it has in 

 man : nor do the vertebrae exhibit that gradual increase in size from below 

 upwards, which they present in him. In the gorilla, orang, and chimpanzee, 

 there are only four lumbar vertebrae ; the number of dorsal vertebrae bearing 

 ribs is thirteen in the gorilla, twelve in the orang, and thirteen in the chim- 

 panzee. The surfaces of the bodies of the vertebras generally, are inclined to 

 the horizon ; and their spinous processes are more powerfully developed than 

 in man, to enable the posterior or erector muscles to support the habitual for- 

 ward inclination of the body. These characters of the spines are particularly 

 noticeable in the upper dorsal and lower cervical region, where they afford 

 increased surface of origin, and greater leverage, for the muscles intended to 

 support the head. The cranium itself has its occipital foramen, and adjoin- 

 ing condyles for articulation with the neck, situated further and further back, 

 as we descend in the Quadrumanous scale ; so that the weight of the head is 

 carried at a mechanical disadvantage, as compared with man ; a disadvantage 

 counterbalanced by the greater development of the spinous processes, and of 

 the posterior cervical muscles. In the lower Quadrumana, such as the ateles 

 or spider monkey, the attitude and mode of progression, on the ground, be- 

 come more decidedly horizontal ; the anterior and posterior limbs being now 

 of nearly equal length, and the hands and feet almost exactly resembling each 

 other in form. In the lowest, so-called, Quadrumana, as in the Lemurs, the 

 erect, or partially erect, position, is only momentarily possible, and progression 

 in that attitude never takes place ; the great toe ranges with the others, and 

 bears a claw. 



12 



