VII.] 



PRIM A TS. 



93 



and flatness of the sternum. It is broadest in proportion 

 to its length in the Siamang (Hylobates syndactylus). In 

 the Orang (Fig 32), each segment of the mesosternum 

 is developed from a pair of lateral ossifications, which 

 commonly remain separate until the animal is about half 



grown. j 



m 



In the lower Monkeys, the presternum is somewhat broad 

 but the bones constituting the mesosternum are elongated 

 and compressed, and are not ankylosed together as in Man 

 and the highest Apes. Their number varies from three to 

 five. In the Howling Monkey 

 (Mycetes) the original two halves of 

 the presternum are separated by a 

 broad fissure, and form a pair of 

 diverging, horn-like, bifurcated pro- 

 cessess (pro-ostea, Parker), which 

 ossify separately, and support the 

 clavicles and first pair of ribs. Ac- 

 cording to Albrecht - this condition 

 of the manubrium is in relation 

 with the enormously developed thy- 

 roid cartilage in the male JE/yosfer, and 

 is therefore a secondarily acquired 

 condition. 



In the CARNIVORA, the sternum 

 (Fig. 33) is generally composed of eight or nine pieces 

 altogether, including the presternum and the xiphisternum. 



The presternum, or manubrium, is long and narrow, 

 somewhat expanded near the front for the attachment of the 



1 The sternum of a young Gorilla in the Museum of the College of 

 Surgeons presents the same condition. 



' 2 Sttr les Elemens Morphologiques dit Manubrium Sterni. (Brussels, 

 1884.) 



JC S 



FIG. 32. Sternum of young 

 Orang (Simla satyrus). ps 

 presternum ; ins mesoster- 

 num ; -i-s xiphisternum. 



