Updated March 11th: The Scott catalogue numbers for this issue are

• 5163 (34¢) Queen Conch shell, serpentine die cut 11¼x10¾
• 5164 (34¢) Pacific Calico Scallop shell, serpentine die cut 11¼x10¾
• 5165 (34¢) Alphabet Cone shell, serpentine die cut 11¼x10¾
• 5166 (34¢) Zebra Nerite shell, serpentine die cut 11¼x10¾
• a. Horiz. or vert. strip of 4, #5163-5166
• 5167 (34¢) Alphabet Cone shell coil stamp, serpentine die cut 9¾ vert.
• 5168 (34¢) Zebra Nerite shell coil stamp, serpentine die cut 9¾ vert.
• 5169 (34¢) Queen Conch shell coil stamp, serpentine die cut 9¾ vert.
• 5170 (34¢) Pacific Calico Scallop shell coil stamp, serpentine die cut 9¾ vert.
• a. Horiz. strip of 4, #5167-5170

Updated January 27th: Here is the pictorial first-day postmark for this issue: It measures 2.87″ x 1.14″.

Updated December 22nd: Postal Bulletin

On January 28, 2017, in San Diego, CA, the U.S. Postal Service® will issue the Seashells Postcard Rate stamps (Non-denominated, priced at 34 cents) in four designs, in a pressure-sensitive adhesive (PSA) pane of 20 stamps (Item 119600) and a PSA coil of 100 stamps (Item 749900). The stamps will go on sale nationwide January 28, 2017.

Four new postcard stamps celebrate the wonder of seashells. Each stamp depicts one iconic shell found in North American waters: the alphabet cone, the Pacific calico scallop, the zebra nerite, and the Queen conch, commonly known as the pink conch. The highly stylized stamp art expresses a lighthearted, artistic view of shells. The horizontal swaths of white and blue in the background suggest waves washing the shells onto a beach. Art director Greg Breeding designed the stamps. Sergio Baradat created the stamp art.

Stamp Fulfillment Services will not make an automatic push distribution to Post Offices.

How to Order the First-Day-of-Issue Postmark:
Customers have 60 days to obtain the first-day-of-issue postmark by mail. They may purchase new stamps at their local Post Office, at The Postal Store® website at http://www.usps.com/shop, or by calling 800-782-6724. They should affix the stamps to envelopes of their choice, address the envelopes (to themselves or others), and place them in a larger envelope addressed to:

FDOI-Seashells
Stamp Fulfillment Services
8300 NE Underground Drive, Suite 300
Kansas City, MO 64144-9900

After applying the first-day-of-issue postmark, the Postal Service™ will return the envelopes through the mail. There is no charge for the postmark up to a quantity of 50. There is a 5-cent charge for each additional postmark over 50. All orders must be postmarked by March 28, 2017.

There is one philatelic product for the booklet of 20:
•119616 First-Day Cover (set of 4), 2 stamps, $4.48.

There is one philatelic product for the coil of 100:
•749916 First-Day Cover (set of 4), 2 stamps, $4.48.

Technical Specifications:

Issue: Seashells Stamps
Item Number: 119600
Denomination & Type of Issue: Postcard Rate, Non-denominated, Mail-use
Format: Pane of 20 (4 designs)
Series: N/A
Issue Date & City: January 28, 2017, San Diego, CA 92199
Art Director: Greg Breeding, Charlottesville, VA
Designer: Greg Breeding, Charlottesville, VA
Typographer: Greg Breeding, Charlottesville, VA
Artist: Sergio Baradat, New York, NY
Modeler: Joseph Sheeran
Manufacturing Process: Offset, Microprint
Printer: Ashton Potter (USA) Ltd. (APU)
Printed at: Williamsville, NY
Press Type: Muller A76
Stamps per Pane: 20
Print Quantity: 150,000,000 stamps
Paper Type: Nonphosphored Type III, Block Tag
Adhesive Type: Pressure-sensitive
Processed at: Ashton Potter (USA) Ltd. (APU)
Colors: Cyan, Magenta, Yellow, Black, PMS7471c Turquoise, PMS Cool Gray 5c
Stamp Orientation: Vertical
Image Area (w x h): 0.73 x 0.84 in./18.54 x 21.34 mm
Overall Size (w x h): 0.87 x 0.98 in./22.10 x 24.89 mm
Full Pane Size (w x h): 5.35 x 4.93 in./135.89 x 125.22 mm
Plate Size: 400 stamps per revolution
Plate Numbers: “P” followed by six (6) digits
Marginal Markings: Front: Plate numbers in four corners of pane
Back: ©2016 USPS • USPS Logo • Two barcodes (119600) • Plate Position Diagram • Promotional Text

Technical Specifications:

Issue: Seashells Stamps
Item Number: 749900
Denomination & Type of Issue: Postcard Rate, Non-denominated, Mail-use
Format: Coil of 100 (4 designs)
Series: N/A
Issue Date & City: January 28, 2017, San Diego, CA 92199
Art Director: Greg Breeding, Charlottesville, VA
Designer: Greg Breeding, Charlottesville, VA
Typographer: Greg Breeding, Charlottesville, VA
Existing Photos: Sergio Baradat, New York, NY
Modeler: Joseph Sheeran
Manufacturing Process: Offset, Microprint
Printer: Ashton Potter (USA) Ltd. (APU)
Printed at: Williamsville, NY
Press Type: Muller A76
Stamps per Coil: 100
Print Quantity: 500,000,000 stamps
Paper Type: Nonphosphored Type III, Block Tag
Adhesive Type: Pressure-sensitive
Processed at: Ashton Potter (USA) Ltd. (APU)
Colors: Cyan, Magenta, Yellow, Black, PMS7471c Turquoise, PMS Cool Gray 5c
Stamp Orientation: Vertical
Image Area (w x h): 0.7037 x 0.84 in./17.87 x 21.34 mm
Stamp Size (w x h): 0.8437 x 0.98 in./21.43 x 24.89 mm
Plate Size: 768 stamps per revolution
Plate Numbers: “P” followed by six (6) single digits
Coil Number Frequency: Plate numbers every 32nd stamp below stamp image

From the USPS, September 20, 2016:

Four new postcard stamps celebrate the wonder of seashells. Each stamp depicts an iconic shell found in North American waters: the alphabet cone, the Pacific calico scallop, the zebra nerite, and the Queen conch, commonly known as the pink conch. The highly stylized stamp art expresses a lighthearted artistic view of shells. Horizontal swaths of white and blue in the background suggest waves washing the shells onto a beach. Art director Greg Breeding designed the stamps. Sergio Baradat created the stamp art.