This story raises more questions than it does answers.  In the 1890s, the Giant Palouse earthworm was said to be common, three feet long, able to spit, and smelling like lilies.  "Samples" were sent to a researcher who formally described the worm for science.  

The earthworm was thought to be extinct in the 1980s.  It requires unspoiled prairie land to roam deep in its underground lairs, and the Palouse prairies have been torn up to make way for crop lands.  

Armed with a new earthworm research tool, a pair of researchers have uncovered new specimens.  The earthworm is shy, and almost impossible to capture.  It lives deep, and by the time you shovel down to it, it's slipped away into the earth.  Along come some clever earthworm fans who jab electrical probes deep into the earth, and drive the worms up towards the surface with electrical current.  (It's all very Dune, isn't it?!)

The researchers positively identified their samples as being Giant Palouse earthworms, based on dissection and microscopic examination of its various organs.  Sadly, the earthworms are only about a foot long, they don't smell like lilies, and they don't spit.

Question #1: how did everyone in the 1890s determine that the worm was commonplace?  If it lives that far down in the soil, how were they encountering it?  Even a plow only goes down about a foot.  How did they know?

Question #2: if the worm was scientifically described, did dude just take their word for it on the length?  Did they send in an entire worm to be studied?  And if so, where is it?  And how long is it?

Question #3: how the heck were people discovering that the worm spat and smelled like lilies?  I guess whatever strange earthworm recovery methods they used in the 1890s, they gave people ample time to examine their worms in detail.

Question #4: why are we sure these are definitive samples?  Just because these adult worms are only 10 inches long, that doesn't mean they don't grow bigger.  Maybe this is a dwarf variety.  It happens.

Giant earthworms certainly exist.  There's one in Australia, the Giant Gippsland earthworm, which is blue and can be up to nine feet long.  So it's certainly plausible that there is - or was - a megaworm roaming beneath the Idaho prairires.  Plus there are giant worms in Ecuador, as pictured above.

I mean, it still sounds a lot more like one of the so-called "Fearsome Critters" of the west that were described by lumberjacks trying to outdo each other around the campsite.  Like the hoop snake, which bites its own tail, curls into a circle, and rolls along the ground.  Or the Sidehill Gouger, which has legs longer on one side than the other, thus allowing it to run along steep hills at great speed.

The more I think about it, the more I wonder if early reports of the gigantic Idaho earthworm were actually garter snakes in disguise.  Garter snakes are indeed common in this part of the world, and easily observed and caught.  They don't quite get three feet long.  (But then again, everything gets bigger in the telling, doesn't it?)  They do emit a white goopy substance, although they don't spit it, it's exuded from specialized glands when they get frightened.  And it doesn't smell like lilies - it's designed to be disgusting, so that a predator (or unwary child) will drop the snake in surprise.