Australian 9-D Platypus Sideways Watermark Sg173 Sg191

Hi to all
Perhaps I am missing something, but I can not find the above stamp listed in Gibbons with the sideways watermark inverted.(See photos)
Top stamp is sideways reversed, and bottom is normal sidways, and last is the picture of the stamps mentioned.
Any help would be greatly appreciated.
No, this is not an April Fools Day Joke, Both stamps are genuine.
Regards

Horamkhet

Can you organise your pictures so that you show the correct orientation of the rear of the stamps. The way you have shown them it is hard to tell which way is up on the reverse stamps.

Have you read the footnotes in your SG which points out differences in the watermark orientation in the different issues defined by perforation size.

Regards
Frank

Hi Langtounlad
If you imagine the platypus with its bill facing to the sky, and then flipped over, that is the direction of the watermarks.

Horamakhet

According to the ACSC catalogue, there were three main types for this stamp.
1. Print run started in 1937 and had sideways watermark with the top of crown facing left. Perforated 14 x 13.5
2. Print run started in 1943 and had sideways watermark with the top of crown facing right. Perforated 14 x 14.75
3. Print run started in 1956 and had no watermark. Perforated 14 x 14.75

I'd check the perforations of your two stamps. They appear to be types 1 and 2 mentioned above.

Hi StevieG
Thanks for the info, I do not have the ACSC for that era, so much appreciated
Horamakhet