February 24, 1905.] 



SCIENCE. 



315 



In this instrument the alternations in bright- 

 ness at any point in the field when the slide 

 is moved are beats due to the Doppler effect 

 just as truly as are those heard in the second 

 form of Koenig's experiment. 



Albert B. Porter. 



Chicago, 



January 14, 1905. 



NOTE ON THE BROAD WHITE FISH. 



In the Proceedings of the American Philo- 

 sophical Society of Philadelphia, XLIII., 

 1904, p. 451, plates VIII. and IX., I have 

 wrongly identified the broad white fish, or 

 Coregonus hennicotti Jordan and Gilbert, as 

 the humpback, or Coregonus nelsonii Bean. 

 My error was due largely to lack of material, 

 ignorance of the species from autopsy, and 

 the fact, as I have since discovered, that C. 

 nelsonii does not always exhibit the well-de- 

 veloped hump like that of the type. Possibly 

 when the Siberian forms are carefully studied 

 the nomenclatures of these fishes will be more 

 stable. 



Henry W. Fowler. 

 Academy of Natural Sciences, 

 Philadelphia, February 5, 1905. 



REGENT ZOOPALEONTOLOGY* 

 During the past thirteen years great ad- 

 vances have been made in our knowledge of 

 the ancient mammalian life of North Amer- 

 ica, especially through the explorations in the 

 Eocky Mountain region carried on by the 

 Carnegie, Field Columbian and American 

 Natural History Museums. The long Ter- 

 tiary period has been clearly subdivided into 

 a series of stages and substages. This enables 

 paleontologists to record more accurately than 

 ever before the time of arrival and departure 

 of the larger and smaller quadrupeds from 

 North and South America, Asia, Europe, Af- 

 rica, and to determine more precisely when the 

 connection of North and South America was 

 interrupted by a gulf flowing between the 

 Atlantic and Pacific Oceans, and when the 

 connection was again made by the elevation 



* Abstract of a lecture delivered by Professor 

 Osborn before the Society of Naturalists at the 

 Philadelphia meeting. 



of the Isthmus of Panama; this demonstrates 

 also that a very much closer connection existed 

 between the animal life of Europe and of 

 North America through continuous intermi- 

 gration over the broad land area now sub- 

 merged beneath the Behring Straits. A series 

 of six world maps prepared by Dr. W. D. 

 Matthew clearly exhibit this submergence and 

 emergence of the isthmuses between these 

 great continents. 



Of especial interest is the recent discovery 

 by the Geological Survey of Egypt that the 

 whole race of mastodons and elephants orig- 

 inated in Africa, entered Europe in the mid- 

 dle of the Tertiary and soon afterward found 

 their way into North America and somewhat 

 later into South America. We have now been 

 able to fix very positively the date of actual 

 arrival of these animals in North America. 

 It appears probable that successive waves of 

 migrations of European and Asiatic species 

 of elephants "and mammoths came to this 

 country. In the meantime there survived 

 here from one of the earliest African migrants, 

 the eastern American forest mastodon which 

 lived until comparatively recent times. 



The theory of multiple races or polyphyletic 

 evolution not only of elephants but of horses, 

 rhinoceroses, camels and titanotheres appears 

 to be clearly established through these recent 

 discoveries. It was formerly believed, for 

 example, that the modern horse had a single 

 line of ancestors extending back into the 

 Eocene period; now it appears that in North 

 America there were always four to six entirely 

 different varieties of the horse family living 

 contemporaneously, including slow-moving, 

 forest-living horses with broader feet, and 

 very swift plains-living horses with narrow 

 feet fashioned more like the deer. Interme- 

 diate between these arose the variety which 

 survived and gave rise to the true modern 

 horse. Furthermore, it appears that the mod- 

 ern horses separated from the asses and zebras 

 at a much more remote period than has been 

 generally supposed, and we are now endeavor- 

 ing to ascertain accurately when this separa- 

 tion occurred. 



The same discoveiy of multiple races has 

 been made among the rhinoceroses. In Eu- 



