What can I call a longer passage in an academic work (text equivalent to "Figure")?

Solution 1:

If they are all pieces of another published work,

See excerpt 6.1 on page 43.

An excerpt in writing is a quoted passage taken from a longer work, such as a book, or poem, or an article. Whatever the subject of your writing or the type of writing you intend to compose, excerpts can be used to 'show' readers what it is you want them to understand and remember about the subject.

https://study.com/academy/lesson/excerpt-definition-examples-quiz.html

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Solution 2:

The word "insert" will do.

(SOED) 2. Something set in or inserted. esp. an extra page or pages inserted in a book etc.; a small map, photograph, etc. inserted within the border of a larger one;

Addition so as to dispel the skepticism introduced by user Edwin Ashworth's comment.

ref.