I don't know how old your Charlton guide is but these notes are fairly common and well documented in the current catalogue of Canadian Bank Notes.
$10.00 Jan. 3, 1927 2306420 Wilson/Holt
Charlton cat # 630-14-08 worth $90 in VG and $450 in EF
The C is a check letter. The notes were printed in sheets with identical serial numbers on each note for a given sheet, but the check letters are all different. Each sheet will have notes with different check letter of A, B, C, and D.
$10.00 Jan. 2, 1913 3247076 C E Neill /H S Holt
CH 630-12-08 worth $550 in VG and $2,000 in EF, though these notes trade somewhat below catalogue in lower grades at present.
$5.00 Jan. 2, 1935, 682216 C, Dobson/wilson
CH 630-18-02a worth $65 in VG and $250 in EF.