Vol.. 8, 1922 
PALEONTOLOGY: H. F. OSBORN 
245 
a candle in a dark room. The reflexes resulting in orientation are similar 
to the scratch reflexes in the dog. How it is that they have come to be 
specifically correlated in character and extent with the localization of the 
stimulus in the eye is not known. They are instinctive in nature since 
they are largely independent of experience in the individual in which they 
occur and their origin is doubtless the same as that of other instinctive 
reactions. 
A full description of photic orientation in Bristalis and Erax will be 
published shortly. This paper will contain an extensive bibliography 
including all of the literature referred to above. 
HESPEROPITHECUS, THE FIRST ANTHROPOID PRIMA TE 
FOUND IN AMERICA 
By Henry FairfieIvD Osborn 
American Museum of Nationai. History, New York 
Read before the Academy, April 25, 1922 
This communication to the Nationai, Academy, Tuesday April 25, 1922, 
was simultaneous with its publication in the American Museum novitates.* 
A single small water-worn tooth, 10.5 mm. by 11 mm. in crown diameter, 
signalizes the arrival of a member of the family of anthropoid Primates 
in North America in Middle Pliocene time. The discovery is due to 
Harold J. Cook, consulting geologist. Agate, Nebraska. 
The anthropoid Primate characters of the tooth are confirmed by another 
water- worn third upper molar previously found by William D. Matthew 
in the same beds but not described because it was not sufficiently distinc- 
tive. These two teeth establish the existence in the Pliocene period of a 
new and independent type of anthropoid, intermediate in the structure of 
its grinding teeth between the anthropoid ape and the human type. The 
animal is certainly a new genus of anthropoid ape, probably an animal 
which wandered over from Europe and Asia with the large south Asiatic 
element that has recently been discovered in our Pliocene fauna by Mer- 
riam, Gidley, and others. The generic name Hesperopithecus signifies 
Pitkecus of the Western Hemisphere; its specific name haroldcookii is 
assigned in honor of the discoverer. The tooth actually resembles the 
human type more closely than it does any known anthropoid ape type; 
consequently it would be misleading to speak of this Hesperopithecus at 
present as like the known anthropoid apes; it is a new and independent 
type of Primate and we must seek more material before we can determine 
