15thc perception on swallowtail merlons?

[eggyk]

I found some nice voynichey swallowtail merlons in this manuscript:

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Vatikan, Biblioteca Apostolica Vaticana, Pal. lat. 1362 A
Pietro Vesconte
Land- und Seekarten (Portolane) — Italien, 14. Jh. (1320) 

   
   

Full picture:

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For the dating the website lists this as 14th century, 1320 based on a signiture from Pietro Vesconte, who was active between 1310-1330. The world map from 1448 was supposedly added later. 

The map is of "Akkon", which is Acre, Israel.