22 EDWARD A. WILSON. 



open cracks were always to be found. During blizzards and heavy weather these cracks 

 o-et completely hidden up in snowdrift, and one may see that the seals experience a 

 certain amount of difhculty in finding them again, if they happen to have been lying 

 out while the storm proceeded. In this case one finds them burrowing into the snow 

 with their noses, and when they discover the crack, in all probability by this time half 

 frozen up and filled with snowdrift, they commence with their teeth to work a hole 

 which shall be big enough to let them through. 



Their method of enlarging a crack to make a hole has been more than once 

 observed by members of our expedition in McMurdo Sound, and the evidence is 

 well supported by the condition of the teeth in a really old Weddell's Seal ; this is 

 well exemplified in the sample figured, where the canines and incisors are worn to 

 rounded stumps (Seals, PI. III.). The seal, fixing the canines and incisors of his 

 lower jaw in the solid ice, begins to revolve the upper jaw about them, in this way 

 using the teeth of the lower jaw as the fixed point of a centre-bit while those of the 

 upper act as the cutting edge. This has not, to my knowledge, been previously 

 observed, and it explains not only the very worn condition of the teeth, but also how 

 new seal-holes rapidly appear in a narrow, fresh-formed crack in solid sea ice, even 

 within a few hours, sometimes, of its opening. The seal has been known to work in 

 the same way from below, and in this case one cannot but think that there must be 

 sufficient air-space below the ice for breathing. 



Further examples of the wearing down of the incisors and canines may be seen in 

 Skulls Nos, 47, 48, 78, and 82 of the ' Discovery' Collection. 



To return to the subject of progression, it is obvious that this power of making 

 holes in the ice for entrance to or exit from the water has almost entirely done away 

 with the necessity for any but the most perfunctory methods of progression on 

 ice and land. The hind flippers certainly are never used at all except when the seal 

 is in* the water, and there is no tendency whatever under any conditions to attempt 

 to bring them forward in progression. That there is still free and varied movement 

 in every joint of the hind limb is, however, obvious from the fantastic positions that 

 it assumes when the animal, as he so often does, stretches himself, or when he brings 

 an irritable hind limb forward to be slowly and deliberately scratched by the long nails 

 of the fore limb. The quaint attitudes thus exhibited are exemplified in several of the 

 accompanying illustrations. 



It is interesting to note in this connection, too, that although when lying on the 

 ice these seals are often in a very irritable condition as regards their skin, a repeated 

 and careful search failed to reveal any external parasites at all. It would appear that 

 the animal is quite free from anything of the kind, and one is led to conjecture that 

 the constant irritation as the animals lie sleeping in the sun, is due to the effect of 

 evaporation on the salt water in their hair. It may be that the crystallisation of the 

 salt, and the peculiar eff'ect which drying has upon the hair itself, may cause the 

 irritation, for the hair, instead of lying ffat against the skin as it does when wet, takes 



