28 STUDIKS OF TASMANIAN CETACEA, 



■■ lary notches, pre-maxillfe nearly on a level with adjacent 

 ' parts. Orifice of anteiior nares level with the lower 

 " end of the nasal boss. End of rostrum qviite acute and 

 " broader than deep. Rudimentary alveolar groove dis- 

 '■ tinct distally Proximal end of vomer (A'/r!) is anky- 

 " losed with anterior face of nasals and reaching up to 

 " nasal boss, which has a sliarp median ridge completing 

 " the nasal sei^tum superiorly. Anterior face of nasal 

 " bos3 slightly concave on each side of the median 

 " line." *y' In our skull the alveolar groove can be traced 

 throughout its length, but everything else is duplicated in 

 Trues description. Apparently this American animal 

 was slightly older at the time it came ashore than our 

 specimen was when captured in Tasmania, for the reason 

 stated, when dealing with the cartilaginous bridge between 

 the pre-frontals and the other elements at the vertex of 

 the skull. In the matter of the ethmo-vomerine cartilage, 

 both skulls yield similar evidence, and in a w^ord True"s 

 data makes it absolutely manifest that the ossification of 

 the rostral cartilage has been pushed to an extreme point, 

 as a factor of taxonomy, since the real truth is that it 

 may or may not ossify, and if it does, it is usually late 

 in life in the female sex — but slightly earlier and more 

 strongly in the male. There is a temi>tation to hazard 

 the guess that the almost total reduction of the dental 

 apparatus in ziphoid whales and the conseqvient diversion 

 of nutriment and nerve energy to a more central line may 

 have had something to do with the extra ossific enei-gy that 

 acted upon the ethmo-vomerine cartilage. At the tip of 

 the beak, upon the right side, there is a foraminal groove, 

 most likely vestigial, and obviously the remaining one of a 

 pair, that at one time were fiinctional. This groove ended 

 about an inch from the functional foramen that passed 

 facial nerves to the beak during the life of the individual 

 under study. The alterations to the beak areas bv the 

 reduction of the tooth line and its alveoli have caused the 

 nerves to traverse the beak superficially and the bony 

 tissue is grooved to receive them. A very slight pressure 

 upon the probe (^^) that was passed into the vestigial 

 canal caused it to carry through and appear in the fossa 

 in front of the functional foramen. These canals are func- 

 tional (and symmetrical) in dolphins' skulls, and appar- 

 ently relate to the teeth. Tn the higher mammals the 

 vomer and its incidental pressure upon part of the septal 

 cartilage determines the amount that ossifies — extra pres- 

 sure causing reduction and suspension of the cfsific activ- 



(9) Tiaie, Bull. 73, U.S. Nat. Mus., pp. 50-51. 



(10) This pi-obe wns at the time it appeared externally 17 i inches 

 through the bony tissue of the beak. 



