1893.] CETACEAJS^ GENUS MESOPLODON. 227. 



3, Mesoplodon hectoki (Gray). 



Berardius arnuxii, Hector, Trans. N. Z. 1. ii. p. 27 (1870). 



Smaller Ziphioid Whcde,l\.nox & Hector, Trans. N. Z. 1. iii. p. 125, 

 pis. xiii.-xv, (1871). 



Berardius hectori, Gray, Ann. & Mag. Nat. Hist. ser. 4, vol. viii. 

 p. 117 (1871). 



Mesoplodon hio.vi, Hector, Trans. N. Z. I. vol. v. p. 167 (1873). 



Mesoplodon hectori, Turner, Trans. E. Soc. Edin. vol. xxvi. p. 778 

 (1872) ; Flower, Trans. Zool. Soc. vol. x. p. 416 (1878). 



Since Sir William Flower's memoir on the genus Mesoplodon, no 

 further information has been obtained as to this species, which 

 differs so markedly from the others occurring in the same region, 

 in the absence of a basirostral groove and in the position and form 

 of its mandibular tooth. 



The Kaiapoi specimen (I in the list, p. 218) (Plate XIII. fig. 1) in 

 the Canterbury Museum, which bears the MS. name of M. hectori 

 (and has been referred to by Hector as M. hectori), is undoubtedly at 

 once distinguishable from this species by the presence of a most 

 distinct basirostral groove. In this paper therefore I have placed 

 it under M. grayi. It is just possible that the cranium and the 

 mandible of M. hectori. Gray, figured by Sir W. Flower, may not 

 belong to each other. 



4. Mesoplodox lataedi (Gray). 



Ziphius layardi. Gray, P. Z. S. 1865, p. 358 ; Owen, Crag Cet. 

 p. 12, pi. i. (1870). 



Ziphius (Dolichodon) layardi, Gray, Cat. Seals & Whales B. M. 

 p. 353 (1866). 



Dolichodon layardii, Hector, Trans. N. Z. I. vol. v. p. 166, pi. iii. 

 (1872). 



Mesoplodon longirostris, KrefEt, MS. ; M. guentheri, Krefft, MS. 



Calliodon r/uentheri, Gray, Ann. & Mag. Nat. Hist. ser. 4, vol. vii. 

 p. 368 (1871). 



Dolichodon traversii. Gray, Trans. N. Z. I. vol. vi. p. 96 (1874). 



Mesoplodon fowcri, Haast, P. Z. S. 1876, p. 478 ; id. Trans. N. 

 Z. I. vol. ix. p. 442 (1877). 



Mesoplodon guntheri, Turner, Trans. E. Soc. Edin. vol. xxvi. 

 p. 778. 



I exhibit a figure of the transverse section c (see fig. 2, p. 228) 

 of a specimen in the Wellington Museum, N.Z., whose age was not 

 quite mature (its rostrum, from the maxillary foramen, measured 

 2 feet 3^ inches), in comparison with an example (fig. 1 h) in the 

 Canterbury Museum, and another (fig. 1 a) figured in the ' Chal- 

 lenger ' Eeports by Sir W. Turner. The Wellington specimen 

 was in rather a poor condition, being considerably water-uorn, 

 and having lost by accident part of the mesorostral ossification. 

 The anterior part of the rostral trough was still empty, though 

 presenting a slight increase in the floor of the premaxillaries ; 



