VERTEBRATES FROM MIOCENE, PLIOCENE AND PLEISTOCENE. 95 
BOXE VALLEY FORMATION. 
The Bone Valley formation which lies chiefly in Polk and Hills¬ 
boro counties in southern Florida is approximately if not entirely 
contemporaneous with the Alachua formation. It differs, however, 
in that it presents a marine phase, and as a whole is marine or es¬ 
tuarine in origin. A description of this formation has been given 
and a number of the fossils illustrated in a report on the land peb¬ 
ble phosphate deposits contained in the Seventh Annual Report of 
the Florida State Geological Survey issued in 1915. 
The fossils obtained from the Bone Valley formation include 
two species of rhinoceroses, three hipparions, a camel, two or more 
mastodons, a bear-like carnivore, Agriotherium, and a tortoise. 
With these land animals there is found in the deposits a gavial, 
an alligator, cetaceans and fishes. These fossils are obtained from 
the phosphate mines operating - in Polk and Hillsboro counties. 
NEW PLIOCENE VERTEBRATES. 
ELEPHANTIDAE. 
MAMMUT PROGENIUM? 
Plate 10. 
A mastodon new to Florida obtained recently from the Bone 
Valley formation is of more than ordinary interest because of the 
evident relationship of the species to the Pleistocene mastodon, Mam- 
inut americanum, to which possibly it is directly ancestral. The 
parts found include the lower jaws of one individual, lacking the 
symphysis, and the symphysis of a second individual referred pro¬ 
visionally to this species. These fossils were obtained by the Amal¬ 
gamated Phosphate Company while mining phosphate rock from 
their remarkably productive pit at Brewster, Florida. The matrix, 
some of which was clinging to> the jaw when collected, consists of 
a coarse pebble phosphate conglomerate. From this pit at the same 
level has been found Apliclops and Hipparion, thus fixing definitelv 
the place of the mastodon in the formation. The jaw is that of a 
mature individual, the teeth preserved apparently being the second 
and third true molars. Of these the second molar is somewhat 
worn, while the third molar is just coming into use and shows but 
slight wear on the first and second anterior crests. The second 
