true: the type of anoplonassa forcipata 105 



end of the jaw upturned, but this is quite probably an age character, as 

 in the recent genus Ziphius old individuals have the extremity of the 

 jaw strongly recurved, while in young individuals the angle between the 

 axis of the symphysis and the axis of the rami is very obtuse. 



It appears to me that the evidence that Palaeoziphius belongs to the 

 ziphioids is not convincing, though it is conceivable that the ancestors of 

 the recent genera may have been some such form with a series of func- 

 tional teeth. It has to be remembered that Palaeoziphius, Cetorhynchus, 

 and Mioziphius are all from the upper Miocene, and that Anoplonassa 

 was also probably derived from the Miocene. 



In my opinion Mioziphius is a much nearer relative of Anoplonassa 

 than is Palaeoziphius. That it is of larger size and has a shorter sym- 

 physis does not seem to me to exclude the idea of close relationship. It 

 is a well-known fact that closely allied recent genera of cetaceans, such as 

 Steno and Sotalia, or Steno and Tursiops, among the Delphinidae, differ 

 greatly in the two characters mentioned. In the genus Mesoplodon the 

 length of the symphysis varies very considerably in different species. In 

 the general conformation of the symphysis, in the general form, details of 

 structure, and relative positions of the alveoli, and in the form of the end 

 of the jaw, Mioziphius certainly exhibits a striking resemblance to Anoplo- 

 nassa. These characters, I think, greatly outweigh those of size and of 

 length of symphysis, and make it proper to unite the two genera in a 

 separate section of the Ziphiidae. 



Certain crania, as well as mandibles, are assigned to Mioziphius belgi- 

 cus by Dr. Abel, though he does not give the evidence on which the 

 reference of the former to that genus and species is based. Presuming 

 that these crania and jaws really do belong to the same species, it will be 

 interesting to consider Cope's view, expressed in 1895, that the cranium 

 known as Pelycorhamphus may belong to the same genus as the jaw 

 known as Anoplonassa. 1 



Cope's description of the cranium of Pelycorhamphus indicates a form 

 sharing some of the characters of Choneziphius, with others of Paracetus, 

 Kogia, etc., and having as a peculiar feature the expansion of the proxi- 

 mal end of the vomer, forming a wide basin which overlaps the maxil- 

 lary. There appears to be some trace of this latter character in Meso- 

 plodon layardi, but nothing resembling it occurs in Mioziphius. It 

 seems, therefore, that if Dr. Abel has correctly associated the mandible 

 No. 3854 of the Brussels Museum with the cranium of Mioziphius, Pely- 

 corhamphus has nothing to do with Anoplonassa. I am by no means 



1 Proc. Araer. Philos. Soc, 1895, 34, p. 138. 



