VII. J 



PRIMA TES. 



75 



fibrous tissue, although it is not unfrequently ankylosed in 

 old age. 



The xiphisternum ossifies irregularly and imperfectly. 



The Gorilla, Chimpanzee, Orang, and Gibbons, resemble 

 Man, and differ from the other monkeys in the breadth and 

 flatness of the sternum. It is broadest in proportion to its 

 length in the Siamang (Hylobates syndactylies). 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. 1 



In the lower Monkeys the pre- 

 sternum 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 presternum has 

 in front of it two large diverging horns 

 (pro-ostea, Parker), which ossify sepa- 

 rately and support the clavicles and 

 either the whole or part of the first 

 pair of ribs. 



In the Carnivora, the sternum 

 (Fig. 33) is generally composed of 

 eight or nine pieces altogether, in- 

 cluding the presternum and the xiphi- 

 sternum. 



The presternum, or manubrium, is long and narrow, 

 somewhat expanded near the front for the attachment of 



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

 Surgeons presents the same condition. 



Fig. 33 — Sternum-and sternal 

 ribs of Dog (Cams fami- 

 liaris), \. ps presternum ; 

 ms mesosternum ; xs xiphi- 

 sternum. 



Surge< 



I! 



