8o 



THE STERNUM. 



[chap. 



ossifies from three distinct pairs of nuclei, and a large 

 median fontinelle remains between the first and second 



Fig. 37. — Sternum of Cachalot or Sperm Whale {Pliysctcr juncroccphnhis), .,',. 



pair.^ In the specimen in the Museum of the Royal College 

 of Surgeons, which is very nearly adult, each half of the 



Fig. 38.— Sternum of Greenland Right Whale [Balcena viysticetiis), ^ j. 



presternum {ps) has coalesced with the corresponding 

 half of the first segment of the mesosternum {ms^), but the 



1 I have observed this ha animals evidently of great age. 



