It's by H. F. Arnold, who only ever published three stories, but it remains one of the most popular - and unsettling - from that era in Weird Tales history.
I am myself the modern day night editor and wire editor for three newspapers and a writer and consumer of horror, so of course I love this tale, which is firmly entrenched in Lovecraft territory.
I first learned of this piece thanks to Patton Oswalt, of all people, who did exactly what I'm doing here - discussing 31 horror stories he loves over the month of October - back in 2006.
I'm trying to make this and Michael Shea's "The Autopsy" the only duplicates on the two lists.
Go check out Patton's. He's got some good stuff there!