VERTEBRATES FROM MIOCENE, PLIOCENE AND PLEISTOCENE. 85 
parently a rather close resemblance to Parahippus ( Anchippus ) 
texanus (Leicly).* From that species, however, it differs first of 
all in size, the anteroposterior diameter of the tooth being 16 mm. 
while that of the Texas species according to Gidley is 19 mm. A 
difference may be seen also in the protocone, which in the Florida 
species is more nearly circular, being but slightly elongated antero- 
posteriorly, while the protocone of P. texanus is distinctly elongated, 
although not in a line parallel to the anteroposterior diameter of 
the tooth. The walls of the crochet and hypostyle of the Florida 
tooth are distinctly folded, while in the Texas species they are more 
nearly simple. The fold in the anterior wall of the metaloph 
(crochet) according to Leidy’s statement does not actually touch 
the protoloph in P. texanus nor does the projection from the hypo- 
style connect with the metaloph. In the Florida species the enamel 
wall of the crochet touches the enamel wall of the protoloph. This 
is true also of the hypostyle, and in the worn tooth apparently 
there is connection of the dentine of the metaloph and hypostyle. 
The type of P. texanus which was taken from a well at a depth of 
50 feet in Washington County, Texas, is commonly assigned to 
the Miocene. 
To P. cognatus, the type species of the genus, the resemblances 
are perhaps hardly so close as to P. texanus. Of Parahippus {An¬ 
chippus ) hrevidens (Marsh) Gidley I have seen no specimens, nor 
does the species seem to have been illustrated. The teeth of that 
species, however, are slightly larger, and are described by Gidley 
as having a considerable investment of cement. From Parahippus 
pawniensis Gidley this species differs in that it has a strong median 
rib on the external surface of the molars. The metaloph in the 
upper teeth of P. pazvniensis, moreover, is said to be comparatively 
straight, while in this species it curves backward. From Parahip¬ 
pus coloradensis Gidley this species differs in that the outer walls 
of the paracone and metacone are nearly smooth while in that spe¬ 
cies they are described as being strongly ribbed. 
This species presents close resemblance in the structure of the 
upper molars to Parahippus ( Desmatippus ) crenidens Scott from 
* Journal of the Academy of Natural Sciences, Phila., (2), Vol. vii. The 
Extinct Mammalian Fauna of Dakota and Nebraska, pp. 312-313, pi. xxi, fig. 13, 
1869. 
