294 REPORT OF THE AMERICAN COMMITTEE, 
California, the Oregon Desert, Western Nebraska, and prob- 
ably other localities. The beds are nowhere of great depth. 
The presence of Homo in the beds of this epoch in Oregon 
was indicated by me in 1878. This discovery has been con- 
firmed by the discovery of obsidian implements in place, in 
Western Nevada, as affirmed in a recent publication of Mr. G. 
K. Gilbert of the United States Geological Survey, in Nature. 
This gentleman has expressed the belief that the beds of this age 
are not older than the glacial epoch, because they embrace the 
basis of some of the moraines of some of the ancient glaciers of 
the Sierra Nevada. It remains to be proven, however, that these 
moraines are of true glacial age, since they are of entirely local 
character. The presence of so many mammals of the fauna of 
the valley of Mexico would not support the belief in a cold 
climate. 
The Megalonyx Beds. — This formation is chiefly repre- 
sented in the caves of the Eastern States. Its fauna is as fol 
lows: Present: Megatherium, Mylodon, Megalonyx, Castoroides, 
Amblyrhiza, Arctotherium, Smiiodou, Platygonus, Mastodon, of 
extinct genera; and of recent genera, Sciurus, Arctomys, Jaculus, 
Arvicola, Erethizon, Hydrochoerus, Lagomys, Lepus, Scalops, 
Procyon, Canis, Mustela, Equus, Tapirus, Dicotyles, Cariacus, 
Bos, Didelphys. Absent : Glyptodontidse, Equus crenidens, oeci- 
dentalis, and barcenoei ; Eschatiidse, Holomeniscus. 
It is not certain that this fauna does not owe its peculiarities to 
geographical causes only, and was not entirely contemporaneous 
with the epoch of the Equusbeds. Its relations to that of the 
Plistocene are not yet fully defined. 
PLISTOCENE SYSTEM. 
The following report of this system in North America between 
the Allegheny and Sierra Nevada Mountain ranges has been 
drawn up by Dr. J. W. Spencer. 
The southern limit of the Plistocene deposits — known as the 
Drift — is defined by a line extending from Long Island, irregu- 
larly northwestward across New Jersey and Pennsylvania into 
western New York ; thence stretching in the form of lobes, 
across Ohio (to near Cincinnati), Indiana and Illinois, to near St. 
Louis. It then sweeps round and forms a comparatively nar- 
row zone upon the western side of the Missouri River — to which 
