: This is a standard file extension for a compressed archive (7-Zip). On digital library sites, large text files or image sets of books are often bundled into these archives for download.
: Refers to a section of the book discussing the anatomy of the bee, specifically its "structure of wings, tongue, or sting". tongue.7z
: In this context, it often denotes a "piece" or "part" of a multi-volume work or a specific segment of the digital archive's file structure. : This is a standard file extension for