Dąbrowski has an unidentified “Symbols of the Ancient and Accepted Scottish Rite”, see below. Judging the text in the triangle, it is from France. The lamb appears on the regalia of the 17º degree. It doesn’t appear to be a Paschal Lamb (which has a flag). I don’t know where the lamb / sheep is laying on and to what degree this image refers. Also I don’t know if this image features in other rites or degrees.
In Les Plus Secret Mysteres (1820) a lamb laying on a book with seven seals (like below) and both are displayed on the front of the Ark of the Covenant.
The seven seals which belong to this book, signify the seven Degrees of Masonry; & the lamb laying down on it, which is the Shekhinah, shows us that, He alone is worthy to break the seals, it is only the true Rose Croix who enjoys the privilege of reading in the book that contains the complete doctrine of Masons, & of penetrating the most secret mysteries.
Voss lists the lamb as the first in the chapter about Symbols of the First Degree and explains it as “innocence”.
Dąbrowski P. 212. Year and designer unknown.