48 TRUNK VERTEBRA. [chap. 



S Monkeys (A teles) have mostly 18. Among the Lemurina, 

 \ Loris and Nycticebus have as many as 23 or 24. 



Of thoracic vertebrae, the Gorilla and Chimpanzee have 

 13, the Orang 12, the Gibbons usually 13 ; other Old World 

 Monkeys mostly 12 ; the American Monkeys from 12 to 15 ; 

 the Lemurs from 12 to 16. 



As a general rule the vertebral column, taken as a whole, 

 is straighter than it is in Man, showing a much less marked 

 sigmoid curve. 



Except in the most anthropoid Apes, and a few others, the 

 spinous processes of the anterior thoracic vertebrae lean 

 backwards, and those of the lumbar and some of the poste- 

 rior dorsal vertebrae forwards, so that they converge to a 

 point near the hinder part of the thoracic region, sometimes 

 called " the centre of motion " of the vertebral column. 1 

 This may be between two vertebrae, but more often there is 

 one, which has an upright spine, towards which the others 

 are directed ; this is the " anticlinal vertebra." It is at this 

 point that the thoracic vertebrae begin to change their 

 characters, and assume those of the lumbar vertebrae ; and 

 the simple elongated transverse processes break up as it 

 were into the metapophyses, anapophyses, and lumbar 

 transverse processes, all of which are conspicuous in these 

 animals. 



The transverse processes of the lumbar vertebrae are 

 usually placed lower on the sides of the vertebrae than 

 in Man. 



In Galago the hinder edges of the neural spines of the 

 lumbar vertebrae bear a pair of backward-projecting pro- 

 cesses, which clasp the anterior edge of the succeeding 



1 This disposition of the spines of the trunk vertebrn? is still more 

 marked in many of the inferior mammals, especially the terrestrial 

 Carnivora. 



