John Adams' China Gates bar 42 - only 2 1/8 notes?

How can this be notated? It's 4/4 time and so I expect 8 1/8 notes but there are only 2. I don't understand how this can be, but there it is. This is not the only time this sort of thing happens in the score: it happens before a 'gate' change (though not every gate change), at the bar preceding the bar where the key signature changes for the next gate.

Sometimes there are only 2 1/8 notes (as in this example), other times there are 6 1/8 notes or 4 1/8 notes . But in all cases where it does happen, the following bar is a full 8 1/8 notes.

It would not be correct to insert rests, of course, and still be true to the composer's intention.

Thanks!