FOSSILS FROM THE RIVER PEBBLE PHOSPHATE 
DEPOSITS. 
MASTODON, ELEPHANT AND HORSE. 
Fig. 45 .—Mammut americanum (the American mastodon). Unworn molar 
tooth from Alafia River. Approximately one-half natural size. Collection of 
S. A. Robinson. Length of tooth 18 cm; greatest width 9 cm. The teeth of 
M. americanum are readily distinguished from those of the more primitive mas¬ 
todons of the Bone Valley formation by the fact that the valleys across the teeth 
are open and unobstructed, while in the teeth of the mastodons from the Bone 
Valley formation the cross valleys are obstructed by buttresses. 
Fig. 46.—The Columbian elephant. Side view of an elephant’s tooth, prob¬ 
ably Elephas columbi var. Approximately one-fifth natural size. Fla. Geol. Surv. 
collection No. 3743. From the Caloosahatchee River. Found in the sand and 
muck above the shell marl. Grinding surface of tooth 30 by 15 cm; 5% plates 
per 100 mm. 
Fig. 47.— Equus. A lower tooth from a very large horse. Found at White 
Beach. Collection of Mr. Joseph Willcox. 
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