On the Shell of an aged male Hyperoodon rostratiis. 21 



Shetland. Loch Ranza. 



($ Af,'ed. (J Juv. 



Extreme length of skull, . . . End of beak broken off. 



ft. 

 Height of skull at occipital crests, . . 1 



,, ,, nui.xiliary crests,^ . . 2 



Greatest breadth of anteiior surface of maxillary 



crests, ..... 



Least interval between upper surface of maxillary 



crests, ..... 



Height of maxillary crests above intermaxillary bone, 1 

 Greatest transverse breadth of skull behind orbits, 2 



The skull from Orkney in the British Museum has also 

 the end of the beak broken off. What is left of this skull is, 

 according to Dr J. E. Gray, 5 feet 2 inches long, whilst what 

 is left of my specimen is 4 feet IJ inches. Dr Gray speaks of 

 the maxillary crests as very thick, as nearly touching each 

 other in front of the blow-hole, and as much higher than the 

 hinder part of the skull ; but he does not give their numerical 

 dimensions. In my specimen the maxillary crests in the 

 aged skull were fully a foot higher than in the younger 

 specimen, and whilst in the latter the summits both of the 

 occipital and. maxillary crests were almost in the same hori- 

 zontal plane, in the aged skull the maxillary were 9 inches 

 higher than the occipital crests. But the differences in 

 breadth of the maxillary crests were equally striking. In the 

 younger skull they formed a ridge both on their upper and 

 anterior borders, which was not more than an inch wide at the 

 free edge ; and, whilst the inner surface was almost vertical, 

 the outer surface bulged outwards, and the crest was thickest 

 about the middle. 



In the aged skull each crest was almost vertical on its 

 outer surface ; the inner surface was also nearly vertical for 

 about two- thirds of the distance from the summit, when it 

 became slightly concave, so that the interval between the 

 two (irests, which was at the summit only 1 inch at the 

 narrowest spot, increased close to the intermaxillie to 3 

 inches at the hinder end, and 4J inches in front. AYhilst 

 the greatest breadth of the anterior surface of a crest was 



^ The height of the crests is modified according as the skull is made to rest 

 on the mastoid processes or the pterygoids. 



