THE SIGNIFICANCE OF HUMAN ANOMALIES. 731 



in twisting their bodies when hanging by their fore-limbs to the 

 branches of trees. Again, in apes, the muscle forming the posterior 

 fold of the arm-pit is always prolonged down to the prominence on 

 the back of the elbow. In the long-armed apes this muscle is espe- 

 cially well developed, and serves to swing the whole arm rapidly and 

 powerfully forward — a movement which is of the greatest importance 

 for dexterously grasping remote branches while in the act of climbing. 

 The same prolongation of this muscle is occasionally seen in man, 

 though in a much less developed state, and serves to remind him of 

 the arboreal habits of some of his not very remote ancestors. 



In the gorilla, orang, and chimpanzee a muscle, called the elevator 

 of the collar-bone {levator claviculce), is always present ; this goes from 

 the upper neck-bones to the collar-bone. It is found in about three 

 per cent of human subjects. Other muscles, occasionally found in man 

 in a rudimentary and fragmentary condition, are ones going from the 

 back of the head to the collar-bone or shoulder-blade ; they are w^ell 

 developed in many of the carnivora and ruminants. I have seen them 

 of large size in the lion, deer, etc. ; in those animals they are much 

 used in pulling forward the shoulder. 



In about every other human subject is a small muscle going from a 

 bony spur on the front of the haunch-bones to the muscles in the ante- 

 rior wall of the abdomen. This is the rudiment of the great muscle 

 in the kangaroo, opossum, and other marsupial animals, which supports 

 the pouch where the immature young are carried, and the bony spur 

 is the rudiment of a distinct bone, called the marsupial bone, which 

 always exists in these animals, and gives attachment to the muscles 

 which open and shut the pouch. 



In man the short muscle of the foot which bends the toes is at- 

 tached to the heel-bone, but occasionally the portion going to the fourth 

 and fifth toes is separated from the portion going to the second and 

 third toes, and is attached not to the heel-bone but to the tendon of 

 the long flexor of the toes. In the gorilla only one slip of this short 

 flexor arises from the long flexor of the toes, but in apes we have as 

 a normal condition the arrangement I have endeavored to describe as 

 that occasionally seen in man. 



The brain of man is distinguished from that of the gorilla and the 

 higher apes by having a greater relative size and being more com- 

 plex. The different fissures are not so continuous, and are frequently 

 bridged over by brain-matter. In the brains of criminals, the lower 

 races of mankind, and idiots, according to Benedict, the fissures are 

 very confluent in character, and in some the first frontal convolution 

 is divided into two portions, as in apes. In animals lower in the scale 

 than man, the little brain or cerebellum is more or less uncovered by 

 the posterior lobes of the cerebrum or large brain. This uncovered 

 condition of the cerebellum was well seen in an idiot's brain that I lately 

 had the privilege of examining ; the fissures were also of the conflu- 



