Could anybody help me interpret the underlined part? This is a passage from An American Tragedy by Theodore Dreiser.
And then he was introduced to Zella Shuman and Rita Dickerman, who, for reasons of their own, not the least among which was a desire to appear a little wise and more sophisticated than the others here, came a little late. And it was true, as Clyde was to find out afterwards, that they were different, too―less simple and restricted than quite all of the girls whom Dillard had thus far introduced him to. They were not as sound religiously and morally as were these others. And as even Clyde noted on meeting them, they were as keen for as close an approach to pagan pleasure without admitting it to themselves, as it was possible to be and not be marked for what they were.