534 



ZOOLOGY 



SECT. 



is deposited. In the toothed 

 Whales the carpal s are com- 

 pletely ossified, and are of poly- 

 gonal form : the phalanges are 

 also ossified, with incomplete 

 synovial articulations. In the 

 Cetacea there are sometimes 

 t five digits, sometimes only four : 

 more or fewer have considerably 

 more than the normal number of 

 phalanges sometimes as many 

 as fourteen. The second digit is 

 usually the longest. 



Vestiges of the pelvis are pre- 

 sent in the form of a pair of long 

 narrow bones (Fig. 1148, pelv.) 

 which lie parallel with the spinal 

 column some little distance be- 

 low the region where the chevron 

 bones begin : these appear to re- 

 present the ischia. A second 

 pair of smaller bones which lie 

 close to these in the Whale-bone 

 Whales are apparently vestiges 

 of the femora, and there may be 

 additional vestiges representing 

 the tibiae. 



Skeleton of Sirenia. In the 

 Sirenia (Fig. 1151) the cervical 

 vertebrae do not coalesce, with 

 the exception of two of them in 

 the Manatee. In the Manatee 

 there are only six cervical ver- 

 tebrae, and the neural arches are 

 sometimes incomplete. In the 

 trunk the thoracic vertebrae are 

 numerous; all have distinct 

 facets for the heads of the ribs, 

 and well developed zygapo- 

 physes. The caudal vertebrae 

 are numerous and depressed, 

 with wide transverse processes 

 The ribs are numerous, but few 

 of them are connected with the 

 sternum. The sternum is a broad 

 bone not composed of distinguish- 

 able segments. 



