A BOAR PECCARY, SHOT WHEN FLEEING BEFORE A JAGUAR: GATUN LAKE 
(SEE PAGE 175) 
mals, there are other vertebrates, includ- 
ing certain nocturnal birds, reptiles, and 
fish, that have brilliant eyes at night, as 
is the case with some of the inverte- 
brates, such as spiders, beetles, and crabs. 
Unquestionably the function of the 
tapetum is to give increased keenness to 
the night vision, for in no instance do 
strictly diurnal creatures have reflecting 
eyes, while practically all those of noc- 
turnal habits possess this element of the 
eye, 
On the Panama trip considerable study 
was given this subject, for there were 
missing links that only the tropics could 
supply. Up to this time T had not found 
a single member of the Primates that had 
reflecting eyes, for all tested were diurnal, 
like man. In several countries there are 
species of nocturnal monkeys, but [ could 
never find one in the zodlogical collec- 
tions, and therefore it was with great in- 
terest that I tested the eyes of the little 
owl monkey, whose rescue from a flooded 
forest 1s mentioned elsewhere. 
Selecting a dark night and turning the 
lantern toward it as it sat on the upper 
edge of a porch, its eyes glistened like 
two brilliant diamonds. 
Later, on taking a flashlight picture of 
178 
