SEALS. 217 
certainly in conformance with the formidable cutting teeth and mas- 
sively developed cranial crests of this animal. The Sea Leopard may 
then be regarded as the true carnivore of the group, subsisting on 
fish (and, when they can be obtained, birds), a prey which need both 
catching and holding. For such a réle, requiring both speed, strength 
and activity, besides teeth, its elongated head and body must be 
eminently suited. The three remaining genera are more puzzling. 
In their case no difference of food or habits had until recently been 
recorded. In spite of this I felt sure that the differences of dentition 
must be correlated with differences of habit, however inconspicuous. 
In Lobodon and Leptonychotes poorly developed cranial crests seem to 
indicate that no great violence of jaw action is needed, a character in 
the second case supported by the feeble dentition. In the first the 
teeth, although actually not of feeble size, are not of a shape which 
would lend itself to much use in gnawing and grinding, and the 
small extent to which they are actually worn down bears this out. 
It is then not easy to imagine what can be the use of teeth so unique 
in zoology. Possibly their formation may be explained by some 
words of Monsieur Racovitza. This naturalist’s account of the feed- 
ing of Lobodon is as follows :—* Les Huphausia forment sa nourriture 
habituelle: il nage la bouche ouverte dans les banes de ces crustacés, 
a la fagon des baleines, et en consomme de grandes quantités.” On 
reading these words I was at once struck by the idea that the teeth 
of Lobodon might possibly serve the animal as a sieve whereby to rid 
its mouth of the water taken in with the Huphausia, somewhat after 
the manner of baleen in the Balenide. For this purpose the teeth 
seem to be exactly suited. They do not fit closely, but alternate with 
those of the opposite jaw, so that the cusps form a perfect sieve. I 
believe then that the use of these extraordinary teeth is as I have 
suggested, and I would direct the attention of zoologists who visit 
the Antarctic in the future to what appears to be a point of great 
interest in the history of the animal, and is, I believe, a hitherto 
unparalleled function for the teeth of a mammal. Even, however, if 
my supposition prove to be incorrect, attention should be directed 
to the study of Zobodon, with a view to throw light on the use of its 
teeth. At all events, if extensively used for mastication they would 
speedily show the effects of wear and tear in a far more conspicuous 
manner than they actually do. 
On the Antarctic pack-ice the food of Leptonychotes, like that of 
Lobodon, is said to consist of Luphausia. It teeth are highly different. 
I suggest that the form of the simple but not very strong teeth of 
this species is due to the fact that it is not confined to the pack-ice, 
