128 Sir E. Home on the Tusks of the Narwhale, 



written, or heard asserted upon this subject, and clears up any 

 apparent difference between them. 



In one male skull, in which the sutures were tolerably 

 firmly united, the tusk in the left side is seven feet nine inches 

 long ; a small tusk, nine inches long, is imbedded in the bone 

 on the right side, with a bulb or swelling at its root, and the 

 point six inches from the front of the skull, which is quite 

 solid, and has no external orifice. 



In another male skull, which must have belonged to a 

 younger animal, since the sutures are not completely united, 

 the left tusk is four feet long, and the right one, concealed 

 within the skull, is nine inches and three quarters long, and 

 its point seven and a quarter distant from the front of the 

 skull. In this specimen there is an external orifice leading 

 down to the point of the young tusk, so that in this respect 

 the small tusk is more advanced than in the older one, shew- 

 ing that there is a great variety in the time of the second tusk 

 coming forward. 



The young tusks have not the spiral turns upon them, but 

 are ribbed on the surface, and the ridges have a tendency 

 to the left side. These are milk tusks, since they have come 

 to their full growth, and are quite solid throughout their 

 whole length, similar to the milk tusk of the elephant, which 

 is however only two inches long before it is shed. 



Upon sawing a full grown tusk in a longitudinal direction, 

 I found that, contrary to what happens in the tusks of other 

 animals, there is a hollow tube in the middle through the 

 greater part of its length, the point, and the portion at the 

 root, only being solid. 



From these two specimens, there can be no doubt that the 



