Noooo, that's not the Martian Manhunter, but you gotta admit. The DCU DOES have a hero from Saturn, Jemm, but I guess Earth-2 has a different species hanging out on the ringed planet. Also, completely different physical properties.
Sandman is the only costumed hero in Adventure to date, so it's important to also pay respect to the other adventure genres featured in the book. Westerns, for example. I simply love this death pose, for example.
Mutt & Jeff also scored their own book on this month in history, but I didn't manage access to it, so it's a good thing they were still appearing in All-American. Bud Fisher was far more than a humor strip cartoonist, as you can see from his wonderful drafting here.
The second issue of the quarterly Superman book features only one reprint, and it's of a newspaper strip that would not have appeared in Action Comics. Other firsts include the reveal that Clark Kent's editor at the Daily Star is named George Taylor, and Superman's first use of telescopic vision (in a TEXT story, of all places); it would not appear in a graphic story until Action #20.