10 



Now the head of Cuvicr's London skeleton was very nearly 

 a foot longer than that of the Audierne one ; and with the ex- 

 ception of the width of the occipital foramen in the two 

 animals, which we find to be rather larger in the Audierne 

 specimen, we observe the above relation in size to be well kept 

 up throughout the dimensions of the respective parts of the 

 head. So well kept up, indeed, as to incline us to adopt 

 the idea that these two animals of the Paris Museum must 

 have belonged to the same species. In Cuvier's London 

 and Audierne skulls, as also in the heads deposited in the 

 British and Sydney Museums, the whole length of the head is 

 to the length of the snout always in the same proportion, viz., 

 as 18 to 9. Nevertheless, the Sydney skull differs in a very im- 

 portant point; for while the British Museum upper jaw appears 

 to belong to the same species as the two Paris skulls, not 

 only on account of the above proportion, but also on account 

 of the width of the snout at the ante-orbital notches in all 

 three being always less than one-third of the whole length, 

 this width in the Sydney skull is considerably more than one- 

 third of the whole length. Again, the width of the head 

 between the orbits in the Yorkshire skeleton, Cuvier's 

 London, and the Audierne skulls, is always less than one-half 

 the length of the head. In the Sydney skull it is conside- 

 rably more. In Cuvier's London, and the Audierne skulls, 

 the height of the occipital part of the skull is nearly equal to 

 one-third of the whole length. In the Yorkshire skeleton, 

 according to Beale, it is considerably less ; and in the Sydney 

 skull considerably more ; — so that, in general, the Sydney 

 skeleton is further removed from the Yorkshire skeleton 

 than from the three others. And if these last three 

 be considered to belong to one species, viz., the Catodon 

 macrocephalus of Gray, or Northern Atlantic sperm 

 whale, we may infer that the Sydney skeleton belongs to 

 another species of the same genus, which, whether identical 

 or not with Quoy's Physeter polycyphus, that is, Desmoulins' 

 P. AustraUs, is certainly nearer in structure to the true 

 Atlantic sperm than to the Yorkshire skeleton. The Sydney 



