1920, 50c Orange & Black
(58). Mint N.H., intense color, wide margins, Extremely Fine, Scott
Retail as hinged (Image)
1920, 1b Dark Violet & Black
(59). Lightly hinged, intense colors, extra wide margins, Extremely
Fine Gem (Image) 
1921, 1c Green, "Canal" Double
(60a). Right stamp in right margin horizontal pair with normal, barely
tropicalized original gum, rich colorVERY FINE AND CHOICE EXAMPLE OF THIS DOUBLE "CANAL" ERROR. ONLY TEN WERE PRINTED.
According to Canal Zone Stamps, this error was apparently created on the right vertical row of the left pane. The sheet was placed too far into the press for overprinting of the right pane, causing "Canal" to print on the right stamps of the left pane and "Zone" to print in the gutter. Theoretically, this stamp should exist with overprint missing, but none have been discovered.
With 1969 A.P.S. certificate. (Image)
1921, 1c Green, Booklet Pane
of Six (60b). Lightly hinged, sharp proof-like impression, extra wide
margins, Extremely Fine, a superb pane
(Image) 
1921, 2c Carmine, Ovpt.
Reading Down (61a). Barely tropicalized original gum, intense color on
bright paper, Very Fine and choice, with copy of 1979 P.F. certificate for
block of four, this being the bottom right stamp
(Image) 
1921, 2c Carmine, Double Ovpt.
(61b). Vertical pair, top stamp the variety, bottom stamp normal,
lightly hinged, rich color, Very Fine and choice, only ten were printed
with this close placement of the two overprints and come from the top
horizontal row of one pane, another pane received a skewed second overprint
on approximately 30-40 stamps, with 1979 A.P.S. certificate (Image) 
1921, 2c Carmine, "Canal"
Double (61d). Right stamp in horizontal pair with normal, lightly
hinged, intense colorVERY FINE AND CHOICE. ONLY TEN EXAMPLES OF THE 2-CENT WITH "CANAL" DOUBLE WERE PRINTED.
This variety was printed using the same method as explained in the description of Scott 60a, lot 599. With 1978 P.F. certificate (Image)
1924, 1c Green (67).
Barely tropicalized original gum which is Mint N.H., wide margins,
Extremely Fine, scarce in such superb condition, probably no more than 500
unused copies are known, many of which are off-center and have adherences
on the gum (Image) 
1924, 1c Green, "Zone Canal"
Reading Down (67a). Lightly hinged, rich colors, fresh and Fine, one
pane was printed with 80 stamps "Zone Canal" reading down, ten stamps with
"Zone" only reading down, and ten from the right margin with "Canal"
reading down in the right margin (Image) 
1924, 5c-1b Coat of Arms,
Unissued Set (68var-69var). Complete set of seven values, tropicalized
original gum, rich colors, Very Fine and choice, scarce as only 600 sets
were not destroyed, according to Canal Zone Stamps, these values
were never issued as a decision was made to use U.S. stamps overprinted
"Canal Zone" starting July 1, 1924 (Image)