BEAKED WHALES 213 



6. The pectoral fin is rounded, and not large. 

 The phalanges are not numerous. 



7. There is a dorsal fin, falcate in form. 



8. The throat is marked by at least one pair (? as 

 to Berardius) of gular grooves, similar to those of 

 Baleenoptera and Pkyseter. 



All the Ziphioid whales present these characters. 



They agree with the Physeterinae in having no 

 functional teeth in the upper jaw ; in the general 

 form of the skull ; in the characters of the transverse 

 processes of the dorsal vertebrae ; in the cartilaginous 

 sternal ribs ; and in the throat grooves. 



But the Ziphioid whales differ from the Cachalots 

 in the fewness of their functional teeth and in the 

 existence of a distinct malar bone ; in the latter point 

 they agree with the Mystacoceti. 



It is possible that the Ziphioids also agree to differ 

 from other whales in a small character, which has 

 been noticed at any rate in Hyperoodon, in Mesoplodon, 

 and Zipkius (by Scott and Parker) ; that is in the 

 rounded projection between the flukes of the tail. 



The genus MESOPLODON* consists of moderately- 

 sized whales, 15-17 feet or so in length. Skull with 

 mesethmoid ossified; the nasals are sunk between the 

 upper ends of the pre-maxillae ; single pair of larger 

 or smaller functional teeth in lower jaw, embedded in 



* W. H. FLOWER, "A further contribution to the knowledge of the 

 existing Ziphioid whales, genus Mesoplodon" Trans. ZnoL Soc., x., p. 415. 

 See also AURIVILLIUS, in BHuuig. Svenk. A cad. Handl., xi., 1887; and 

 TURNER mjourn. Anat. Phys., 1886, p. 144. 



