Squalodoii and Zeuglodon. 261 



form of the crenuhitions and the two edges always resemble 

 one another more than in Squalodons. The same author in 

 another paperi says that in S. servatutn the teeth are coated 

 with a thick layer of enamel the surface of which is always 

 " striee*ou guillochee." For the latter word I can get no satis- 

 factory meaning. " Engine-turning '' or the geometric inter- 

 lacing of curved lines does not seem applicable to any ornament 

 described or figured elsewhere. 



Similar references could be nuiltiplied but the quotations are 

 sufficient to show that ornament alone is not sufficient to fix the 

 generic position of an unknown tooth. 



An additional character common to the Northern Zeugiodonts 

 and Squalodonts is the complete separation of the divergent 

 roots of the molar teeth. This character is not shown in any of 

 the corresponding teeth in the Southern forms as far as is 

 known. In Prusqualodon from the Chubut deposits of Argen- 

 tina Lydekkei^ states that in the molariform teeth the fangs 

 have coalesced, but are separated by a deep groove, and he gives 

 a text-figure showing this feature. True'^ says the teeth of Pro- 

 squalodon which he examined did not exhibit the amount of 

 divergence that Lydekker figured. Sanger'* says that the two 

 fangs of his species are connected by an isthmus. The same 

 character of the coalescence of the fangs is shown in M'Coy's 

 type, in the specimens from Mount G-ambier and from Spring 

 Creek. 



The fusion of the roots seems to be of sufficient importance 

 to separate the Southern forms from Squalodon and Zeuglodon 

 alike, and as Lydekker's ProsquaJndon shows the fusion and is 

 undoubtedly Squalodont it will be found advisable, I think, to 

 refer the Australian species to the same family of short-beaked 

 forms. 



In the case of Kekenodon there is a peculiarity. The roots 

 are united in most of the teeth, but in some at least they run 

 parallel, but not quite in contact. Their passage towards com- 

 plete union has not advanced as far as in the Australian species. 

 One tooth, moreover, has a third root, a feature which is more ar- 



1 Lydekker, 1899, p. 921. 



2 True, 1910, p. 450. 



3 Sanger, 1881, p. 298. 



