CETACEA. 485 



skull, the caudal prolongation, and the ribs, are 

 found in that of the Cetacea. The thorax is 

 carried very much forwards, especially in the 

 whale, and the neck is so short as to be scarcely 

 recognisable : for the object of the conformation 

 is here, as in that of the fish, to allow free scope 

 for the movements of the tail, and ample space for 

 the lodgement of its muscles. For the purpose 

 of giving greater power and more extensive at- 

 tachment to these muscles, the transverse pro- 

 cesses of the dorsal and lumbar vertebrae are ex- 

 panded both in length and breadth, and being 

 situated horizontally, offer no impediment to the 

 vertical flexure of the spine. For the same 

 reason the ribs are continued in a line with the 

 transverse processes, and articulated with their 

 extremities, thus giving still farther breadth to 

 the trunk. 



As there is a total absence of hinder ex- 

 tremities, so there is no enlargement of any 

 of the vertebrae corresponding to a sacrum, and 

 the caudal vertebrae are uninterrupted continua- 

 tions of those of the trunk. They develope, 

 however, parts which are met with only among 

 fishes and reptiles, namely, arches composed 

 of inferior leaves* and spinous processes, en- 

 closing and giving protection to a large artery. 

 Although the bones of the legs do not exist, 



* These leaves being formed of cartilage, are generally lost 

 when the bones are macerated for the purpose of preparing the 

 skeleton. 



