FOSSIL VERTEBRATES FROM SAN PEDRO VALLEY—GAZIN 493 
position. The San Pedro Valley jaw represents a form which might 
be regarded as generically distinct from Syvilagus. 
Measurements in millimeters 
I P; P, My 
PANTELODOSLenIOTNGIAM eben se 22s ee es S220 2.8 Dee, 2.2 
RTA SVGrse) Clam CCl ee == earn ee ee 2.3 2.2 2.5 2.5 
1 Approximate. 
Leporid sp. 
A relatively large lower jaw, No. 10530, designated as Species No. 1 
from Benson cannot be referred with certainty to any of the genera 
inasmuch as P,; is missing. Only M, and part of P, are included 
in the jaw, and these are much larger than in Sylvilagus ? bensonensis. 
Order PROBOSCIDEA 
CORDILLERION BENSONENSIS (Gidley) 
The basal portion of a mastodont skull, No. 10538, having nearly 
all the cheek teeth preserved, was described by Gidley (1926, pp. 84— 
86) as Anancus bensonensis. Osborn (1936, pp. 565-566) in his 
monograph on the Proboscidea reallocated this species to Cordillerion, 
regarding it as close to the species Cordillerion andium and C, edensis. 
The cheek teeth were described as brachydont and semibunodont. 
M? is trilophodont, and M? tetralophodont with a fifth loph in an 
incipient stage of development. 
A referred tusk in the collections of the American Museum was 
described by Gidley as being about 4 feet long and 4 inches in diameter 
and of the nearly straight and twisted variety with a wide band of 
enamel extending along nearly the entire length. There is no cer- 
tainty that C. bensonensis had this type of tusk, but Gidley states that 
the form of the tusk “agrees exactly with that of the alveolus in the 
type of Anancus bensonensis.” 
Mastodent sp. 
In a footnote Gidley (1926, p. 85) mentioned occurrence at the 
Benson locality of a mastodont tusk quite unlike that regarded as 
belonging to Cordillerion bensonensis. The specimen “was too badly 
shattered and displaced to be preserved but it showed by the natural 
mold left in the matrix which had surrounded it that it was of the 
short, thick, much curved, and rapidly tapering variety; also, there 
was no evidence of an enamel band.” 
