>>>It's not possible- worms can't speak English.
>>>
>>>(you deserved that ;-) )
>>
>>That's one explanation, but for the sake of argument, suppose the statements were translated truly from worm language.
>
>A fourth worm joined at the end. Or they are going in a circle since you did not say a straight line.

The puzzle will remain open 24 hours or until solved.

Fourth worm is possible, but Occam's razor cut it into little pieces.

I said "in a line" - did not say "in a closed line". Topologically, it doesn't matter whether the line is a zig-zag, squiggly or straight, as long as it doesn't divide the plane into multiple regions. In practical terms, even if they were on a circle, but one with radius about twice longer than their total length, the first worm would still say "two worms BEHIND me", because they'd be too far in the other direction.