Apes and Monkeys. 



7 



sacral vertebrae. The column is divided into a cervical or neck 

 portion, a dorsal or back portion, to which ribs are joined, a 

 lumbar or loin region, a sacral or pelvic region, and, lastly, a 

 coccygeal or tail region. 



Let us now see wherein there is agreement or difference 

 between man and the lower animals in respect of the constituents 

 of the spinal column. 



In man the number of vertebra? in the entire column is 

 usually 33, though sometimes there are 34. In the three 

 higher apes, the gorilla, the chimpanzee, and the orang, the 

 number of vertebrae is the same as in man, namely, 33. In the 

 lowest ape, the gibbon, the number is 35. There are 7 neck 

 vertebrae in man and apes alike. The spinous processes attached 

 to these neck vertebrae are simple in all the apes and monkeys 

 except the chimpanzee, which has two out of the seven present- 

 ing a characteristic peculiar to the cervical vertebrae of man, 

 the processes being split into two branches, or forked. 



The number of the vertebrae in the back and loins is from 19 

 to 24 in the inferior monkeys; 18 in the lowest ape; 17 in the 

 chimpanzee and gorilla, which is the usual number in man. 



The spinous processes of the vertebrae in the lumbar region 

 are all turned forward, or " anteverted," in the inferior monkeys 

 and quadrupeds, as a condition of their having to walk on all 

 fours ; while the corresponding processes in the region of the 

 back are turned tailwards, or " retroverted." Now in none of the 

 apes are the lumbar spinous processes anteverted in the least, but 

 approach very near to man, in whom the spinous processes of all 

 the dorso-lumbar vertebrae are retroverted — essential conditions 

 of the erect or semi-erect attitude in progression. 



The sacral vertebrae are in the lower monkeys from 5 to 7 ; 

 in all the apes there are 5 as in man. Though these 5 vertebrae 

 are all welded together to support the viscera in the erect atti- 

 tude, yet only 3 are true sacral in the sense of giving attachment 

 to the pelvic girdle. The other two are, properly speaking, 

 caudal vertebrae. 



The true sacral vertebrae, then, are three in number, the same 

 as are found in all the apes and even the inferior monkeys. The 

 apes agree with man in having two false sacral vertebrae, forming 

 really part of the caudal region. 



The caudal vertebrae have been divided into true and false ; 

 the true are those into which the spinal canal is continued, or 

 those remaining vertebrae posterior to the sacral, which have 

 rudimentary rings ; the false caudal vertebrae are those into 

 which the spinal canal is not continued, but simply consist of 

 button-like segments. 



The number of true caudal vertebrae in the inferior monkeys 



