70 



PROFESSOR TURNER ON ZIPHIUS CAVIROSTRIS 



Shetland, the lachrymal bone was very distinct, and the mastoid part of the 

 temporal was a separate ossification. The tympanic bone also, as figured by 

 Van Beneden, closely corresponds in shape to that of the Shetland cranium. 



There is, however, greater difficulty in coming to a positive conclusion as to 

 the specific position of the cranium from Aresquies described by Gervais, and 

 that from Buenos Ayres by Burmeister. These skulls agree in possessing the 

 characteristic hollow at the base of the beak, but they differ from the specimens 

 above referred to, in possessing an open meso-rostral canal, extending along the 

 whole length of the beak, and in the consequent absence of a meso-rostral bone. 

 Gervais' specimen not only had rudimentary teeth, but it is also stated by 

 Fischer that the nasal fossae were not so deflected to the left, and the hollow of 

 the prenasal fossa was not so great as in the skull from Arcachon. Gervais 

 himself does not regard these differences as sufficient to form a new species, 

 and refers the Aresquies cranium to Z. cavirostris. Fischer, however, con- 

 siders them to be of specific value, and gives the specimen the name of Z. Ger- 

 vaisi. Burmeister's specimen was admittedly a young male, and not only were 

 rudimentary teeth, as in Gervais' specimen, present in the gum, but a strong 

 cylindrical cartilage occupied the canal between the two intermaxillary bones. 

 Should the non-ossification of the anterior end of this cartilage be a persistent 

 condition in these animals, even in adult life, then they would undoubtedly have 

 to be regarded as forming species distinct from cavirostris. But if the want of 

 ossification of the cartilage is due, like the presence of rudimentary teeth, merely 

 to the youth of the animals — and as the conversion of the anterior part of this 

 cartilage into bone is altogether an exceptional occurrence in the cetacea, it is 

 possible that it may not take place in the genus Ziphius until towards the end 

 of the period of ossification — then these characters cannot be adduced as satis- 

 factory evidence of a specific difference. I am disposed, until further informa- 

 tion has been obtained regarding this question, to rank provisionally these 

 crania also with cavirostris, which will include therefore the following speci- 

 mens : — 



Ziphius cavirostris. 



Fos, Bouches du Rhdne, 



Aresquies, HeYault, . 



Corsica, 



Cape of Good Hope, 



Arcachon, 



Cape of Good Hope, 



Buenos Ayres, 



Villa Franca, 



Shetland, 



Cuvier. 



Gervais. 



Doumet. 



Van Beneden. 



Fischer. 



Gray and Owen. 



Burmeister. 



Haeckel. 



Turner. 



