Vintage 1978 USPS Block of 20 Owls Wildlife Stamps Scott 1760-1763 Mr Zip MNH

Plate block of 20 vintage 1978 USPS se-tenant, multi-color, 15-cent commemorative stamps. Copyright United States Postal Service 1978. Mint/Never hinged. Full original gummed back.  AMERICAN OWLS (WILDLIFE CONSERVATION USA) Face Value= $3.00 Scott Catalog #: 1760-1763 Issue Date: August 26, 1978 Printed By: Bureau of Engraving and Printing Printing Method: Lithographed, engraved Color: Multi Features one of the following series of numbers: 38794, 38796, 38798, 38799, 38800, or 38806, and a running Mr. Zip figure holding an envelope in the selvage. When multiple blocks are offered, the series numbers in the selvage may vary from the one listed in my description and photo. There are 5 sets of 4 unique designs in this block featuring: Great Gray Owl; Barred Owl; Saw-Whet Owl; Great Horned Owl. The stamps were designed by artist Frank J. Waslick.