VERTEBRATES FROM MIOCENE, PLIOCENE AND PLEISTOCENE. 97 
teeth, from the hard rock phosphate deposit, Nos. 1167 and 1246, 
are referred to this species. 
The anteroposterior measurement of the type specimen is 13^2 
mm.; the greatest transverse measurement is 13 mm. The antero¬ 
posterior measurements of specimen No. 1167, which may be a milk 
tooth is 11 mm., while the transverse measurement is 11 mm. The 
enamel bordering the lakes in this small species is very much com¬ 
plicated,. The inner column of the tooth is elipsoidal in the cross 
section. The species may be known as Hipparion minor. 
A metacarpal referrable either to H. ingenuum or to the smaller 
species, H. minor , was referred to the writer for examination in 
April, 1916, by Mr. Anton Schneider. On the back side of the 
bone may be seen the roughened surfaces for the attachment of met- 
acarpals two and four. This roughened surface extends from one 
side of the bone 140 mm. while on the other extends about 120 mm. 
Between these scars the bone is slightly grooved, thus differing 
from the same bone of H. plicatile, which according to Leidy and 
Lucas has a ridge between the two digits. At the distal end this 
bone is more flattened on the front surface than is that of the mod¬ 
ern horse. There is also a groove at the outer and inner side of 
the trochlea, which received digits two and four. The bone is 
nicely preserved and the groove which received the artery may be 
seen lying at the side of the digit. 
The measurements of this bone are as follows : 
Length of bone-185 mm. 
With proximal articular face- 23 mm. 
Width of distal articular face-- 24 mm. 
A smaller metacarpal from the hard rock phosphate deposits is 
indicated by specimen No. 1589, the transverse width of proximal 
articular surface of which is 21 mm. 
Of the hipparions, four species have now been described from 
Florida. Of these the largest is Hipparion princeps, the type and 
only known specimen of which was found on Peace Creek and hence 
is of uncertain geologic age. The two species, Hipparion plicatile 
and Hipparion ingenuum,were described by Leidy from the Alachua 
clays, but are present also in the hard rock phosphate deposits and 
in the Bone Valley formation. Of the four species, H. princeps is 
by far the largest, while the one here described as H. minor is much 
