May 2, 1902.] 



SCIENCE. 



689 



middle of a great lake. Siuee the surround- 

 ing clays are usually almost destitute of 

 bones, it is difficult to understand liow the 

 dead carcasses of so many animals were 

 driven or drawn as by a magnet to so lim- 

 ited an area. Accepting the other theory, 

 however, we have seen how, during the 

 rainy season, the deer, tapirs and other ani- 

 mals are driven to the islands over the flood 

 plains of the great South American rivers. 

 Since in exceptionally high freshets the 

 lower of these islands become destroyed, it 

 is not difficult to understand how great 

 nvuubers of these animals must annually 

 perish, and indeed it is a well-known fact 

 that frequently great numbers of them are 

 caught on low islands and, driven by the 

 rising waters to more limited confines, they 

 are finally all drowned when the island 

 becomes entirely submerged. To such or 

 similar conditions the great deposits of 

 bones in the Oligocene and Miocene de- 

 posits of the West may owe their origin. 



These facts, together with those brought 

 forward by Dr. Matthew in his article 'Is 

 the White River Tertiary an ^olian For- 

 mation' {Am. Naturalist, May, 1899), have 

 driven Professor Hatcher, contrary to his 

 earlier opinion, to reject the theory of a 

 great lake and accept that of smaU lakes, 

 flood-plains, river channels and higher 

 grass-covered pampas as the conditions 

 prevailing over this region in Oligocene 

 and Miocene times. 



Me. EiVEL Douglass, of Princeton, in a 

 communication on 'The Upper Cretaceous 

 and Lower Tertiary Section of Central 

 Montana,' pointed out that the finely ex- 

 posed section of Cretaceous and Lower 

 Tertiary rocks near the Musselshell River 

 in Montana has been considerably affected 

 by the disturbances that produced the 

 mountains a little farther to the westward, 

 so that erosion has exposed the different 

 formations from what is apparently the 

 Jurassic to the Torre.jon. He maintained, 



(1) that there are beds below the Fort 

 Pierre, which have Laramie flora and 

 fauna; (2) that the Livingston, Arapahoe 

 and Denver beds correspond in age with 

 the upper portions of what has been caUed 

 Laramie ; and (3) that the Fort Union beds 

 are of the same age as the Torrejon in 

 New Mexico. 



Professok W. B. Scott, of Princeton, in 

 a paper on 'South American Mammals,' 

 confined his remarks to the Edentata of 

 the Santa Cruz (Miocene) beds of Pata- 

 gonia. Veiy curious is the absence from 

 these beds of the existing families of the 

 ant-eaters and the true or arboreal sloths, 

 while armadillos, glyptodonts and ground- 

 sloths are most abundantly represented. 

 The armadillos are nearly all of aberrant 

 type and very peculiar in some respects; 

 only one species seems to be ancestral to a 

 species of modern times. 



The glyptodonts are very small and in 

 remarkable contrast to the giant forms of 

 the Pleistocene. 



The ground-sloths are relatively small, 

 as compared with the huge representatives 

 of this group wliich in Pleistocene times 

 spread over nearly the whole of North and 

 South America. In the Santa Cruz beds 

 are found the probable ancestors of nearly 

 all the Pleistocene genera. Of especial in- 

 terest on this occasion is the newly dis- 

 covered genus which seems to be the an- 

 cestor of Megalonyx. The latter was first 

 discovered by President Thomas Jefferson 

 and described in an early volume of the 

 Transactions of this Society. 



Samuel N. Rhoades, of Audubon, N. J., 

 in a paper on the 'Mammals of Pennsyl- 

 vania and New Jersey,' said that Pennsyl- 

 vania and New Jersey, on account of their 

 geographic position and the consequent 

 variety of the faunal environments af- 

 forded by the two extremes of the elevated 

 Alleghanian summits and the sandy mari- 

 time plains of the southeastern coast line, 



