Netherlands Scott 142-46

Are these 1924-26 Gull Wing stamps unwatermarked, watermarked 158, or what is the differentiation between these and the subsequent 164-71 series that have the 202 watermark?

The 1924 series has no watermark

The 1926 series has the watermark Circles.

I assume you're relying on a Scott catalogue. It's a common complaint that Scott doesn't indicate essential information about a series (watermark, perforation, printing method, etc.) if that info is the same as for the previous series, or the one before that, or the one before that . . .. In other words, Scott doesn't provide that info unless it represents a change from last time it provided that sort of info. In your case, you'd have to go all the way back from 1924 to 1864 to find the word "Unwmk" at the head of the series #4-6. Annoying, because you have to hunt backwards and could well miss the info you need. Gibbons, Michel and others typically provide the pertinent info for each series, even when it's the same as for the immediately preceding one.