James Comey Posts '8647' in Seashells, Accused of Threatening Donald Trump

James Comey shared some controversial digits on social media ... and now federal officials are calling for a criminal investigation, claiming it's a call to assassinate President Trump.

The former director of the FBI took to Instagram Thursday to share a post with the number '8647' written out on a sandy shore in seashells ... later deleting it after some accused Comey of making a threat on Trump's life.

If ya don't know ... to "86" someone is hospitality shorthand for throwing them out of somewhere -- usually a bar or restaurant. But 86 could also be taking someone out in a more violent way ... depending on how the numbers are used.

So Comey's post could mean he wants to throw Trump out of office ... or -- if you're Donald Trump Jr. ... Comey's plotting to take Trump out of the Oval in a box.

Trump Jr. wrote, "Just James Comey causally [sic] calling for my dad to be murdered. This is who the Dem-Media worships. Demented!!!!”

For his part, Comey claims he shared the pic because he came across the seashells on the beach and assumed it was a political message -- though he adds he didn't know what it meant and didn't realize some have used it to call for violence against the president.

Comey wrote, "It never occurred to me but I oppose violence of any kind so I took the post down."

Homeland Security Secretary Kristi Noem announced the department and the Secret Service are investigating Comey's social media threat ... claiming he "called for the assassination" of Trump.

James Comey served as the FBI director from 2013 to 2017 ... but, President Trump dismissed him -- calling him a "real nut job" in meetings with foreign dignitaries. Comey has since repeatedly fired off at the president.

Whether that means he'd actually threaten the president seems like a stretch ... but, the two really don't like each other -- so, we can't totally rule it out.