BRITISH FOSSIL CETACEA 



Prof. Van Beneden figures 



Fir.. 14. 



Zijjhiu.1 demirostris. 

 Mesodiodon densirosire, Duv.^ 



a mandible of Ziphius Sowerbii^ after a pliotoj^raph 

 of tlie original in the Museum of Cliristiania, trans- 

 mitted to him by Prof. Boeck. The teeth are small, 

 and situated a little nearer the hind part of the 

 symphysis than in the Havre specimen (fig. 12), 

 but it may well be a mere individual variety. The 

 specimen was found on the coast of Norway, the sex 

 unknown — may be inferred to have been female from 

 the size of the teeth in the male, fig. 13, from our 

 own coast, and as contrasted with the size of the teeth 

 in the female specimen stranded at Ostend, and de- 

 scribed by M. B. Dumortier.^ 



Of the Cetacean representing the Memdiodon 

 densirostris of Duvernoy, the sex is unknown ; the 

 skeleton was sent by M. Leduc from the Sechelles 

 Islands to the Garden of Plants, Paris, in 1839; it 

 was most probaljly a male, showing a greater relative 

 size of the developed pair of mandibular teeth than in 

 Ziphius Soioerbii, with concomitant depth of the part 

 of the jaw supporting them, chiefly due to growth of 

 the alveolar border. But all this testifies to no more 

 than specific value, if, indeed, it truly means that. 

 The position of the teeth, more remote from the sym- 

 physis, tells better for specific distinction than their size. 



A further degree of departure from symmetry 

 than in Ziphius Soicerbii and Z. m'lcropterus is mani- 

 fested in the naso-maxillary region (fig. 14, 22')- 

 The prefrontal (14) is ossified throughout its rostral 

 extent, forming the summit of the ridge, a form which 

 the compression and upward convergence of the pre- 

 maxillaries (22) give to the upper surface of the ros- 



^ "Note sur un Mesoplodon Sowerbiensis de la cote de 

 Norwege," in 'Bulletins de I'Acad. 11. de Belgique,' t. xxii, 

 1866. Dr. Gray, in the ' Cetacea of the Erebus and Terror,' 

 pi. V, figs. 1 and 2, also follows De Blainville (' Nouvelle Diet. 

 d'Hist. Nat.,' t. ix, p. 1/7) in giving a termination usually 

 significative of locality — "Sowerbiensis;" I retain the common 

 form, indicative of the individual — Sowerbii. 



2 ' M^moires de I'Academie Royale de Bruxelles,' 4to, torn, 

 xii, 1839. 



' lb., pi. ii, fig. 4. 



