212 A BOOK OF WHALES 



known, and which is fairly abundant, the Ziphioid 

 whales were entirely unknown to science until the 

 beginning of the present century ; and up to the 

 year iS/i only some thirty individuals had been 

 caught or stranded. 



The Ziphioid whales agree in the following assem- 

 blage of characters : 



1. The functional teeth are limited to one or two 

 pairs, which are only developed in the mandible. In 

 addition to these there are a number of small teeth 

 in both jaws, which are not recognisable in skulls, as 

 they come away with the gums, and are hidden by 

 them during life. 



2. The skull is characterised by the marked prom- 

 inence behind the nares, by an elevation of the 

 maxillae (exceedingly developed in Hyperoodoii), by 

 the long rostrum, by the large solid pterygoids which 

 meet in the middle line, and by a distinct and separate 

 malar bone. 



3. The vertebrae are not more than fifty in number ; 

 their spines (in the dorsal and lumbar regions) are 

 very long ; the transverse processes of the neural 

 arches of the dorsal vertebrae, as a rule, cease abruptly 

 near to the end of the series, and are replaced upon 

 the succeeding vertebrae by similar processes which 

 arise from the bodies of the vertebrae {Hyperoodon 

 is exceptional). 



4. The ribs are not more than ten pairs ; the 

 sternal ribs are permanently cartilaginous. 



5. The blow-hole is crescentic, with the concavity 

 forwards. 



