FOSSIL WHALES 387 



big as the last joint of one's little finger, which float by 

 millions in the Arctic Ocean. The whalebone whales, after 

 letting their huge mouths fill with the sea-water in which 

 these creatures are floating, squeeze it out through the 

 strainer formed by the whalebone palisade on each side 

 by raising the tongue and floor of the mouth. The water 

 passes out through the strainer, and the nourishing 

 morsels remain. 



Some fossil jaws and skulls of whales from miocene 

 and older tertiary strata are known which tend to connect 

 the toothed whales with those mammals not modified for 

 marine life. But the approach in that direction does not 

 go very far. The extinct whales called Squalodon have 

 tusk-like front teeth and molars which have the outline of 

 a leaf with a coarsely " serrated " edge. The bones of the 

 face are also, in them, more like those of an ordinary 

 mammal than is the case with modern toothed whales. 

 The snout is not so long, and the bones which form it are 

 a little more like those of a fox's snout than are those of 

 the dolphin's " beak." But on the whole it is astonishing 

 how little we know of fossil whales. We have yet to 

 discover ancestral forms possessing small hind legs, but 

 whale-like in other features. Some day a lucky " fossil- 

 hunter " will come upon the remains of a series of whale- 

 ancestors probably of Eocene age, and we shall know the 

 steps by which a quadruped was changed into a cetacean 

 just as we have recently learned the history of the 

 development of elephants. We know even less about the 

 ancestry of bats and the steps by which they acquired 

 their wings than we do about the history of whales. 

 These discoveries await future generations of men when 

 " cuttings" and "pits" and quarries shall have been made in 

 the rest of the earth's surface to the same extent as they 

 have been in Europe and in parts of the American 

 continent. 



