Tarzan the Terrible Mass market paperbound - 1969

From the book:Silent as the shadows through which he moved, the great beast slunk through the midnight jungle, his yellow-green eyes round and staring, his sinewy tail undulating behind him, his head lowered and flattened, and every muscle vibrant to the thrill of the hunt. The jungle moon dappled an occasional clearing which the great cat was always careful to avoid. Though he moved through thick verdure across a carpet of innumerable twigs, broken branches, and leaves, his passing gave forth no sound that might have been apprehended by dull human ears. Apparently less cautious was the hunted thing moving even as silently as the lion a hundred paces ahead of the tawny carnivore, for instead of skirting the moon-splashed natural clearings it passed directly across them, and by the tortuous record of its spoor it might indeed be guessed that it sought these avenues of least resistance, as well it might, since, unlike its grim stalker, it walked erect upon two feet - it walked upon two feet and was hairless except for a black thatch upon its head; its arms were well shaped and muscular; its hands powerful and slender with long tapering fingers and thumbs reaching almost to the first joint of the index fingers. Its legs too were shapely but its feet departed from the standards of all races of men, except possibly a few of the lowest races, in that the great toes protruded at right angles from the foot.