298 A BOOK OF WHALES 



to be divided into tranverse processes proper, and 

 metapophyses on the fifth dorsal. The former 

 gradually move up towards the anterior zygapophyses, 

 which they entirely supersede on the twelfth vertebra. 

 The latter processes move down and become (on the 

 ninth) fused with the process of the centrum, to which 

 the capitular head of the rib is attached. The 

 arrangement of these tubercles and processes of the 

 vertebrae is related to a singular disposition of the ribs, 

 which is unique among Cetaceans, and is more like 

 that of the Cachalot and Ziphioid whales. The 

 anterior vertebras have a process springing from the 

 neural arch for the tubercular attachment of the rib ; 

 between each two vertebrae (half on each) is a facet 

 for the capitular attachment of the rib. In the fifth 

 vertebra the facet is confined to the anterior edge of 

 the body of that vertebra ; and therefore on this 

 vertebra and those following each rib is solely 

 attached to its own vertebra. As far as the seventh 

 each rib has a double attachment, but on the eighth; 

 or ninth the two facets of insertion have, as already 

 mentioned, coalesced ; from this point, therefore, the 

 ribs are single-headed. 



In having only three lumbar vertebrae Inia is 

 remarkable among whales. It is a point of likeness 

 to the Sirenia. These vertebrae are compressed and 

 ridged below. There seem to be eleven chevron 

 bones. 



The ribs are thirteen pairs the sternal ribs being 

 cartilaginous as in the Physeteridae. It is possible 

 that only two pairs of these reach the sternum, which 



