CETACEA OF THE NEW ZEALAND SEAS. 575- 



True, from the North Atlantic. The essential character is the 

 position of the teeth. Other characters which these species have 

 in common are the broad and deep rostrum and the long mandi- 

 bular symphysis ; also, the dorsal fin is placed far back and the 

 teeth completely covered by the gums. In Alesoplodon, as it is 

 now proposed to restrict it, the teeth are always placed near the 

 posterior end of the symphysis so that the two species comprising 

 Pcdkea apparently form a natural group in which the teeth, as 

 pointed out by Dr. Harmer (Report Cetacea on British Coasts 

 1918, p. 21, 1919), possibly correspond with the anterior pair of 

 Berarditis. 



The reduction of the teeth from four to two in the Ziphioid 

 Whales is interesting. Birardius is perhaps the most primitive 

 of the recent genera and has usually four teeth, but in a skull in 

 the Dominion Museum, Wellington, only the anterior pair is 

 present. In Ziphius and Hyperoodon it is the anterior pair that 

 is retained, but in Mesoplodon the posterior pair only is present. 

 Paikea differs from Mesoplodon in possessing only the anterior 

 pair of mandibular teeth. 



Paikea hectori. 



Berardius hectori Gray, 1871, Ann. Mag. Nat. Hist. ser. 4,. 

 vol. viii. p. 117 ; Hector, 1873, Ann. Mag. Nat. Hist. ser. 4, vol. xi. 

 p. 106. Berardms arnuxii (not Duvernoy) Hector, 1870, Trans. 

 N.Z. Inst. vol. ii. p. 27. " Ziphid Whale," Knox & Hector^. 

 1871, 1. c. vol. iii. p. 125, pis. 14, 15. Mesojylodon knoxi Hector, 

 1873, 1. c. vol. V. p, 167. Mesoplodon hectori Gray, Flower, 1878, 

 Trans. Zool. Soc. vol. x. p. 416, pis. 71, 72; Forbes, 1893 Proc' 

 Zool. Soc. 1893, p. 227. 



Known only from the following specimen : — - 



Titahi Bay, Cook Strait. — Cast ashore January 1866. Skull 

 in British Museum. All the i-eferences quoted refer to this, 

 specimen. Basirostral groove absent. Foramina of fifth nerve 

 level. 



Ziphius. 



Ziphius G. Cuvier, 1823, Ossem. Foss. vol. v. p. 350, pi. ; type,.. 

 Z. cavirostris Cuv. Hypodon Haldeman, 1841, Proc. Acad. Nat. 

 Sci. Philad. vol. i. p. 127 ; type, Delphinus desmaresti Risso {=H. 

 cavirostris). 



If Ziphius and Xiphias be considered variations of the same 

 word, then Ziphius Cuvier, 1823, is preoccupied by Xiphias Linne, 

 1758, a genus of fishes, and the next valid name to be used for the 

 genus of whales is Hypodon 'KaXdemaxi, 1841. Professor David 

 Starr Jordan points out to me that Ziphius seems to have 

 been purposely so written by Cuvier perhaps to make it clearly 

 different from Xiphias, which name was also used by the same ■ 

 author. 



