THE ORDER CETACEA. 125 



sternum itself. There is but one actual sternal rib on 

 each side, which is fairly articulated with the sternum ; 

 whilst the others are, as in most other mammalia, con- 

 nected to that bone by a thick and powerful intervening 

 cartilage, of which only the first five pair are real true 

 ribs, and form any attachment to the sternum: the 

 others are united to each other as the false ribs usually 

 are, and the last three are not connected at all ; conse- 

 quently, we not improperly denominate them floating- 

 ribs. The fourth rib is the longest, and measures nine 

 feet in length ; the others gradually diminish as they 

 approach the fourteenth, which is the smallest. The 

 appearance of the chest as a whole will give the spec- 

 tator a very good idea of the framework of a small sail- 

 ing vessel ; and it is impossible to form any accurate 

 idea of the dimensions of this cavity, without making an 

 examination of the interior: there only it is that a true 

 conception can be formed. 



The Sternum or Breast-bone. — This bone, when con- 

 trasted with the immense dimensions of the chest, is 

 very small and spongy in its texture ; and the layer of 

 compact osseous tissue covering it is so thin as hardly 

 to be perceived. The shape bears some rude resem- 

 blance to a cross, the apex or top of which is carried 

 forward. This bone gives attachment to the first rib on 

 each side, and is composed of three bones connected by 

 cartilage. It has two plain surfaces, and exhibits no- 

 thing else worth mention. 



The Bones of the Pelvis. — The pubic bones, which I 

 have already cursorily mentioned, may not unaptly be 

 considered as appendages of the spine. They are ex- 

 tremely small, and each has somewhat a triangular 

 shape ; but one of the angles is elongated upwards, and 

 they bear altogether no small resemblance to the marsu- 



