The other day I was looking up WWI body armor and helmets. I discovered some really interesting things, like the Ford Model 8 Helmet and the Dean Panoply (a suit of plate armor designed by Bashford Dean, curator of the Met's armor exhibit). Both were supposed to protect soldiers mainly from shrapnel.

Two other helmets caught my eye but I've been unable to find any information on them.

The one on the right:
[ Linked Image ]

and especially this helmet, again on the right:
[ Linked Image ]

This one looks like an armet or a close helm! The website where I found it captioned it and the helmets next to it as French WWI helms. The two on the left are modified Adrian helms, so they're probably French, but the "close helm" on the right is puzzling.

Any clues on what exactly these helmets are?

If you haven't seen it already, here is an interesting book on experimental ww1 era armor. (published shortly after the war)
It goes into detail about the armor designed by different nations during the war.
-http://archive.org/stream/helmetsbodyarmor00d...0/mode/2up
The helmet on the right in the first photo looks like this one:
-http://archive.org/stream/helmetsbodyarmor00d...6/mode/2up
It was an experimental American design that the text says was uncomfortably balanced, and they didn't bother making one out of ballistic steel.

You can also read about visored french helmets starting on page 88.
-http://archive.org/stream/helmetsbodyarmor00d...8/mode/2up

I have read the book, and it contained no information on the French helmet on the right in my second picture. It was nonetheless a fascinating piece with a huge amount of information on armor, helmets, and shields in WWI and with some information on earlier armor as well.

For example, it briefly discusses siege armor from the 16th to the 19th centuries, and mentions plate armor from the 18th century. Dean mentions that some of the combatants in the siege of La Rochelle were shot dozens of times with muskets but survived unharmed due to their very heavy siege armor, and that some commanders and sappers in the American Revolution wore armor, but he doesn't cite sources often or well enough. Maybe I should start a thread on armor in the age of muskets?