FOSSIL VERTEBRATES FROM SAN PEDRO VALLEY—GAZIN 513 
Horse teeth found in deposits at Pleistocene Lake Cochise, not 
far from the San Pedro Valley, were regarded by Gidley *° as repre- 
senting three species. I doubt, however, that more than one is rep- 
resented and this may well be Zquus pacificus or a large EF. occidentalis. 
These specimens average much larger than the teeth from Curtis 
ranch, and the Pleistocene stage represented may be much later. 
The Curtis ranch teeth do not differ appreciably in size from mate- 
rial Hay * described as Equus laurentius from Hay Springs, Nebr., 
although the patterns exhibited are not much alike. The Curtis 
ranch upper teeth have somewhat more concave walls between the 
outer styles and the enamel plates in the walls and lakes are in 
general either more arcuate or trend somewhat more oblique than in 
the Hay Springs paratype. Typical /. lawrentius, and in particular 
EP. nevadanus from Manhattan, Nev., make a marked approach to the 
type of teeth seen in &#. caballus. The Curtis ranch teeth, though 
clearly of the Hguus type, do not seem to be so far removed from 
the Plesippus stage as does much of the better known Pleistocene 
material. 
A few upper teeth, apparently from one individual, No. 11597, found 
near a powder mill a couple of miles south of the Benson locality 
seem to represent “quus rather than Plesippus and may be from the 
Curtis ranch level although the occurrence is geographically nearer 
to the Benson locality. ‘These teeth are of about the same size and 
show somewhat the same type of enamel pattern seen in upper teeth 
from Curtis ranch proper. 
Order ARTIODACTYLA 
Camelid sp. 
A camel of considerable size is present also in the Curtis ranch 
fauna. The material representing this form consists of a right maxil- 
lary portion, No. 12870, with P* to M’, and the proximal and distal 
portions of a fused radius and ulna. P? is lacking in the dental 
formula of this animal, as was probably true of the Benson dentition, 
also the cheek teeth are very similar to those in the older form, but 
appear a little larger. The difference in size may be due principally 
to the greater wear suffered by the Benson teeth. In the Curtis ranch 
specimen the teeth are not in an early stage of wear, nevertheless the 
length of the series including P* to M? is seen to be about 200 mm. 
This is estimated because M° is not complete posteriorly. 
The dentition in No. 12870 is comparable in size to that indicated 
for Gigantocamelus fricki Barbour and Schultz *t from Lisco, Nebr., 
89 Kirk Bryan and J. W. Gidley, Amer. Journ. Sci., vol. 11, pp. 481-484, 1926. 
#0. P. Hay, Proc. U. S. Nat. Mus., vol. 44, pp. 584—591, fig. 27, 1913. 
41q). H. Barbour and C. B. Schultz, Bull. Univ. Nebraska State Mus., vol. 2, No. 2, p. 21, 
1939. 
