The following is from this website:

http://www.couchgenweb.com/civilwar/19thindx.html

LOGAN, H.A. PVT -Age 22. Enl 25 Oct 1861 in Pike Co, AR. Captured 11 Jan 1863 at Arkansas Post, AR & sent to MP Camp Douglas, IL 8 Feb 1863 then to City Point, VA 10 Apr 1863. Paroled 1 May 1865 at Greensboro, NC.

The rest of those in Company D appear to have enlisted on that date in Polk County so I'm thinking the Pike County reference is a typo. I'd say they formed in Polk County, AR.

It's good that you're passing this information on and good luck with your efforts!