For the table of contents, check at the bottom of this post below the image. Linderman was adopted into the Blackfoot, Crow, and Cree tribes, and Napa, the "Old-Man" god of the book's title, is especially associated with Blackfoot storytelling traditions.
The book is available at Internet Archive, Hathi Trust, and Google Books.
WHY OUR SIGHT FAILS WITH AGE
WHY CHILDREN LOSE THEIR TEETH
HOW THE SKUNK HELPED THE COYOTE
WHY THE WEASEL is WHITE
OLD-MAN AND HIS NEW WEAPONS
LOOKS AT THE STARS
CA-MEE-NO-WA-SIT
STRIKES-AND-KILLS
OLD-MAN'S COURTING
BILLY BENT AND THE ECHO PEOPLE
OLD-MAN AND THE SUN-DANCE
WHY THE DOGS HOWL AT NIGHT