Correct; due to age and use none of these prints have their original leaders. The edge markings are at the typical one-foot intervals.
Until anything turns up, I'll assume they may be Ansco. Ansco made b/w camera film as well as color; I don't honestly know if they made release positive or not; but again I'll assume they did as all the other manufacturers did too.
Apropos of nothing, I recently bought an old splicer at an antique/junk shop, and in the box with it was a still-full but cemented-shut bottle of Ansco film cement probably from the 1940's. It's labeled for "Nitrate Or Safety," and contains an extensive poison warning on the back label with antidotes both external and internal. "Contains acetic acid. May cause blisters if in contact with skin. Wash off with water." Seems an unnecessarily hazardous mixture to me...