PEBBLE PHOSPHATE DEPOSITS. 
77 
that the valleys across the teeth as seen on the unworn grinders, 
are open, not being blocked by buttresses from the conules. The 
tusks likewise lack the band of enamel which characterizes the ear¬ 
lier mastodons. Associated with the American mastodon in the river 
pebble phosphate deposits may be found occasionally teeth of the 
earlier forms washed in from the older formations. This associa¬ 
tion is found, however, only in streams that cut across the Pliocene 
or Miocene formations. 
Horses of the genus Equus were present in Florida during Pleis¬ 
tocene and possibly also during the late Pliocene, their remains be¬ 
ing found in numbers in the river pebble phosphate deposits and 
elsewhere throughout the State. The parts preserved include for 
the most part the teeth and occasional bones. Several species of 
Pleistocene horses have been described from Florida as follows: 
Equus caballas, E. Icidyi and E. littoralis. Associated with the 
horses of this modern genus is found in the river pebble deposits 
horses of the extinct genus Hipparion. As in the case of the masto¬ 
don this association is noted only in the bed of streams that cut into 
Pliocene formations. 
The bison obtained from the river pebble phosphate deposits rep¬ 
resents an extinct species, probably Bison latifrons. The deer, tapir 
and manatee, however, are scarcely distinguishable from the living- 
species. 
The sloths, now confined to South America, extended in Plei¬ 
stocene time over a considerable part of the United States, their re¬ 
mains being found at different localities throughout the State in 
the river pebble phosphate deposits and elsewhere. Glyptodonts, 
a division of the Edentates now extinct, likewise extended their 
range into North America during Pleistocene time. They are 
found in Florida in the river pebble phosphate deposits and at some 
other localities. 
Armadillos, or armadillo-like animals, are represented in the 
Florida Pleistocene by the genus Chlamytherium, which in some 
respects is intermediate between the Glyptodonts and the Arma¬ 
dillos. Parts of the skeleton or plates from the carapace of a species 
of this genus have been obtained from Peace Creek, White Beach, 
Hillsboro River, and Vero. Distinctive characters of the genus are 
found in the molar teeth which are elongated from front to back," 
the larger teeth being two or three times as long as broad. On the 
exterior of the tooth is a broad deep furrow which partially divides 
