I just found this review of a short story accidentally left in draft mode. It's another from the LibriVox collection-- Short Ghost and Horror Collection 010-- that I was listening to about a year ago.
"The People of the Pit"
by Abraham Merritt
A tale of the weird in the Lovecraftian tradition. (Or at least I believe it's Lovecraftian... Honestly, that genre is not my expertise. It seems that Merritt and Lovecraft were contemporaries, but I suppose an author's works can be "Lovecraftian" even if s/he wrote before Lovecraft lived-- if you use the term to mean than there's a similarity in themes and atmosphere more than that one was inspired by the other.)
The most effective element of the story (in my ever-so-humble of opinions) was the escaped man's physical deformity from prolonged crawling and the instinctive creeping motions he continued to make-- beyond his own control.
...With that said, I wonder how often Lovecraftian horror is actually scary. I'm not sure why, but the little of it I've read generally doesn't give me the same creepy feeling that I more frequently experience when reading other types of horror. I'm not sure why. Maybe invisible slugs with lights for heads are just too far-fetched to terrify so practical a reader as myself. ;o)
Maybe I just haven't read the right things, yet.
I don't dislike this style of story-- and it can be unsettling-- but it's rarely ever outright scary (again, in my limited experience).