124 THE NATURAL HISTORY OF 



in consequence of their having to support the whole 

 weight of the chest, with the heart, lungs/ &c. &c. ; to- 

 gether with the fins or swimming paws, and shoulder 

 bones. This portion of the spine is curved ; the con- 

 vexity is upwards : by this means the cavity of the chest 

 is greatly enlarged. 



The Bones of the Loins are sixteen in number, and 

 bear considerable resemblance to the preceding, and are 

 without any articulating surfaces ; but it may be here 

 observed, that there exists not the slightest vestige of 

 any abdominal limbs : and they are found attached to 

 these bones, by means of muscles, two little bones, 

 forming the ossa pubis ; and this forms the only vestige 

 of a pelvis. But I shall revert to this subject presently. 



The caudal Vertebra, or those approaching towards 

 the tail, are eighteen in number, and have bony ap- 

 pendages at their inferior surfaces, with the exception of 

 the eight nearest to the tail, where the appendages dis- 

 appear. This portion of the spine tapers towards the 

 extremity; and, where it joins the tail, it exhibits a 

 slight curve, the convexity of which is placed inferiorly. 



Of the Ribs. — These are fourteen on each side, and 

 form the walls of the chest. The structure of these 

 bones is dense, firm, and compact ; which, with their 

 size and thickness, renders the animal capable of resist- 

 ing the most violent shocks : with the exception of the 

 first, which is almost vertical, the others take a more 

 posterior direction. The head of the first rib is double, 

 and articulated with the transverse processes of the 

 seventh and eighth vertebrae by means of tubercles re- 

 ceived into the articulated fossae or cavities of the verte- 

 brae. The dimensions of this rib are very considerable, 

 and the sternal extremity of it is much larger than the 



