species, notably the Greenland seal (Phoca grœnlandica), the Bearded seal or square flipper (P. barbata), the Ringed seal (P. hispida), the Floe-rat (P. fœtida), the Hooded or bladder-nosed seal (Cystophora cristata). Of these probably the Greenland seal is the commonest. These animals assemble in immense herds, especially on the ice in Newfoundland seas. "In Greenland the annual catch was estimated at 33,000, while that in Newfoundland used to exceed 500,000, and in Jan Mayen seas the total number killed each year was fully 30,000." Fortunately the killing of these seals, like that of the fur seals, is now regulated by law, and although they may sometimes be over-killed, yet there is not altogether reckless slaughter. The bearded seal is the largest of Arctic seals, and although it is not so large as some Antarctic species, yet it may attain a length of about ten feet. Like other mammals in Spitsbergen, all these seals have been largely killed out in that archipelago.
The birds of the Polar Regions are a characteristic feature, and again there is the striking fact that, although Arctic lands teem with many species of birds, there are, with the exception of the migratory Chionis, no Antarctic land birds. This is probably due in part to the geological reasons that explain the absence of mammals, in part to the obvious difficulty
