450 THE VERTEBRATE SKELETON. 



twelve or thirteen of which are thoracic. The anterior 

 thoracic vertebrae have short centra and high backwardly- 

 directed neural spines, the lumbar vertebrae have large for- 

 wardly- and downwardly-directed transverse processes with 

 expanded ends. Metapophyses, anapophyses and hypapophyses 

 are all present. In the Agouti (Dasyprocta) the convergence 

 of the neural spines to a centre of motion is very strongly 

 marked. 



In the CARNIVORA the trunk vertebrae are nearly always 

 twenty or twenty-one in number; in the genera Felis and 

 Canis thirteen of these are thoracic and seven lumbar. The 

 anterior thoracic vertebrae have long back wardly-p rejecting 

 neural spines, while the posterior thoracic and lumbar vertebrae 

 have shorter and thicker neural spines which project slightly 

 forwards. In the Pinnipedia there is no change in the direc- 

 tion of the neural spines, and anapophyses are but little deve- 

 loped. 



In the INSECTIVORA the number of trunk vertebrae varies 

 much from nineteen thirteen thoracic and six lumbar in 

 Tupaia, to twenty-four nineteen thoracic and five lumbar 

 in Centetes. The development of the various processes varies 

 in accordance with the habits of the animals, being great in 

 the active forms, slight in the slowly moving or burrowing 

 forms. In Talpa and Galeopithecus the inter vertebral discs 

 of the thoraco-lumbar region instead of being cartilaginous 

 have ossified forming intercentra, a condition met with in 

 very few mammals. 



In the CHIROPTERA there are seventeen or eighteen thoraco- 

 lumbar vertebrae, eleven to fourteen of which may bear ribs. 

 The development of processes is slight. 



Among PRIMATES the number of trunk vertebrae is gene- 

 rally nineteen, of which twelve to fourteen bear ribs ; in man 

 and the Gorilla and Chimpanzee the number is, however, 

 seventeen, and in the Orang (Simia) sixteen. In some of the 

 Lemuroidea there are as many as twenty-three or twenty-four. 



